diff --git a/README.md b/README.md
index 7b92f73b9e..b30bda0cb5 100644
--- a/README.md
+++ b/README.md
@@ -116,6 +116,25 @@ collaborators:
   # * `maintain` - Recommended for project managers who need to manage the repository without access to sensitive or destructive actions.
   # * `triage` - Recommended for contributors who need to proactively manage issues and pull requests without write access.
 
+# See https://docs.github.com/en/rest/deployments/environments#create-or-update-an-environment for available options
+# Note: deployment_branch_policy differs from the API for ease of use. Either protected_branches (boolean) OR custom_branches (array of strings) can be provided; this will manage the API requirements under the hood. See https://docs.github.com/en/rest/deployments/branch-policies for documentation of custom_branches. If both are provided in an unexpected manner, protected_branches will be used.
+# Either removing or simply not setting deployment_branch_policy will restore the default 'All branches' setting.
+environments:
+  - name: production
+    wait_timer: 5
+    reviewers:
+      - id: 1
+        type: 'Team'
+      - id: 2
+        type: 'User'
+    deployment_branch_policy:
+      protected_branches: true
+  - name: development
+    deployment_branch_policy:
+      custom_branches:
+        - main
+        - dev/*
+
 # See https://docs.github.com/en/rest/reference/teams#add-or-update-team-repository-permissions for available options
 teams:
   - name: core
diff --git a/lib/plugins/environments.js b/lib/plugins/environments.js
new file mode 100644
index 0000000000..9e2f59eaf8
--- /dev/null
+++ b/lib/plugins/environments.js
@@ -0,0 +1,180 @@
+const Diffable = require('./diffable')
+
+const environmentRepoEndpoint = '/repos/:org/:repo/environments/:environment_name'
+
+module.exports = class Environments extends Diffable {
+  constructor (...args) {
+    super(...args)
+
+    if (this.entries) {
+      // Force all names to lowercase to avoid comparison issues.
+      this.entries.forEach(environment => {
+        environment.name = environment.name.toLowerCase()
+      })
+    }
+  }
+
+  async find () {
+    const {
+      data: { environments }
+    } = await this.github.request('GET /repos/:org/:repo/environments', {
+      org: this.repo.owner,
+      repo: this.repo.repo
+    })
+    return Promise.all(
+      environments.map(async environment => {
+        if (environment.deployment_branch_policy) {
+          if (environment.deployment_branch_policy.custom_branch_policies) {
+            const branchPolicies = await this.getDeploymentBranchPolicies(
+              this.repo.owner,
+              this.repo.repo,
+              environment.name
+            )
+            environment.deployment_branch_policy = {
+              custom_branches: branchPolicies.map(_ => _.name)
+            }
+          } else {
+            environment.deployment_branch_policy = {
+              protected_branches: true
+            }
+          }
+        }
+        return {
+          ...environment,
+          // Force all names to lowercase to avoid comparison issues.
+          name: environment.name.toLowerCase()
+        }
+      })
+    )
+  }
+
+  comparator (existing, attrs) {
+    return existing.name === attrs.name
+  }
+
+  changed (existing, attrs) {
+    if (!attrs.wait_timer) attrs.wait_timer = 0
+    return (
+      (existing.wait_timer || 0) !== attrs.wait_timer ||
+      this.reviewersToString(existing.reviewers) !== this.reviewersToString(attrs.reviewers) ||
+      this.deploymentBranchPolicyToString(existing.deployment_branch_policy) !==
+        this.deploymentBranchPolicyToString(attrs.deployment_branch_policy)
+    )
+  }
+
+  async update (existing, attrs) {
+    if (existing.deployment_branch_policy && existing.deployment_branch_policy.custom_branches) {
+      const branchPolicies = await this.getDeploymentBranchPolicies(this.repo.owner, this.repo.repo, existing.name)
+      await Promise.all(
+        branchPolicies.map(branchPolicy =>
+          this.github.request(
+            'DELETE /repos/:org/:repo/environments/:environment_name/deployment-branch-policies/:id',
+            {
+              org: this.repo.owner,
+              repo: this.repo.repo,
+              environment_name: existing.name,
+              id: branchPolicy.id
+            }
+          )
+        )
+      )
+    }
+    return this.add(attrs)
+  }
+
+  async add (attrs) {
+    await this.github.request(`PUT ${environmentRepoEndpoint}`, this.toParams({ name: attrs.name }, attrs))
+    if (attrs.deployment_branch_policy && attrs.deployment_branch_policy.custom_branches) {
+      await Promise.all(
+        attrs.deployment_branch_policy.custom_branches.map(name =>
+          this.github.request(`POST /repos/:org/:repo/environments/:environment_name/deployment-branch-policies`, {
+            org: this.repo.owner,
+            repo: this.repo.repo,
+            environment_name: attrs.name,
+            name
+          })
+        )
+      )
+    }
+  }
+
+  remove (existing) {
+    return this.github.request(`DELETE ${environmentRepoEndpoint}`, {
+      environment_name: existing.name,
+      repo: this.repo.repo,
+      org: this.repo.owner
+    })
+  }
+
+  reviewersToString (attrs) {
+    if (attrs === null || attrs === undefined) {
+      return ''
+    } else {
+      attrs.sort((a, b) => {
+        if (a.id < b.id) return -1
+        if (a.id > b.id) return 1
+        if (a.type < b.type) return -1
+        if (a.type > b.type) return 1
+        return 0
+      })
+      return JSON.stringify(
+        attrs.map(reviewer => {
+          return {
+            id: reviewer.id,
+            type: reviewer.type
+          }
+        })
+      )
+    }
+  }
+
+  deploymentBranchPolicyToString (attrs) {
+    if (attrs === null || attrs === undefined) {
+      return ''
+    } else {
+      return JSON.stringify(
+        this.shouldUseProtectedBranches(attrs.protected_branches, attrs.custom_branches)
+          ? { protected_branches: true }
+          : { custom_branches: attrs.custom_branches.sort() }
+      )
+    }
+  }
+
+  async getDeploymentBranchPolicies (owner, repo, environmentName) {
+    const {
+      data: { branch_policies: branchPolicies }
+    } = await this.github.request('GET /repos/:org/:repo/environments/:environment_name/deployment-branch-policies', {
+      org: owner,
+      repo,
+      environment_name: environmentName
+    })
+    return branchPolicies
+  }
+
+  toParams (existing, attrs) {
+    const deploymentBranchPolicy = attrs.deployment_branch_policy
+      ? this.shouldUseProtectedBranches(
+          attrs.deployment_branch_policy.protected_branches,
+          attrs.deployment_branch_policy.custom_branches
+        )
+        ? { protected_branches: true, custom_branch_policies: false }
+        : { protected_branches: false, custom_branch_policies: true }
+      : null
+    return {
+      environment_name: existing.name,
+      repo: this.repo.repo,
+      org: this.repo.owner,
+      wait_timer: attrs.wait_timer,
+      reviewers: attrs.reviewers,
+      deployment_branch_policy: deploymentBranchPolicy
+    }
+  }
+
+  shouldUseProtectedBranches (protectedBranches, customBranchPolicies) {
+    if (protectedBranches || customBranchPolicies === undefined || customBranchPolicies === null) {
+      return true // Returning booleans like this to avoid unexpected datatypes that result in truthy values
+    } else {
+      return false
+    }
+  }
+}
diff --git a/lib/settings.js b/lib/settings.js
index fe7e6f8780..cf2da95db5 100644
--- a/lib/settings.js
+++ b/lib/settings.js
@@ -38,6 +38,7 @@ Settings.PLUGINS = {
   repository: require('./plugins/repository'),
   labels: require('./plugins/labels'),
   collaborators: require('./plugins/collaborators'),
+  environments: require('./plugins/environments'),
   teams: require('./plugins/teams'),
   milestones: require('./plugins/milestones'),
   branches: require('./plugins/branches')
diff --git a/package.json b/package.json
index 7372a6b14b..d6aba3d2c1 100644
--- a/package.json
+++ b/package.json
@@ -16,7 +16,7 @@
     "lint:peer": "npm ls >/dev/null",
     "test:unit": "jest 'test/unit/'",
     "test:unit:watch": "npm run test:unit -- --watch",
-    "test:integration": "jest --test-timeout=10000 'test/integration/'",
+    "test:integration": "jest --test-timeout=20000 'test/integration/'",
     "test:integration:debug": "LOG_LEVEL=debug DEBUG=nock.* run-s test:integration"
   },
   "author": "Brandon Keepers",
diff --git a/test/fixtures/environments-config.yml b/test/fixtures/environments-config.yml
new file mode 100644
index 0000000000..b9bd55058e
--- /dev/null
+++ b/test/fixtures/environments-config.yml
@@ -0,0 +1,81 @@
+environments:
+  - name: changed-wait-timer
+    wait_timer: 10
+
+  - name: changed-reviewers-type
+    reviewers:
+      - id: 1
+        type: User
+      - id: 2
+        type: User
+
+  - name: changed-reviewers-id
+    reviewers:
+      - id: 1
+        type: Team
+      - id: 3
+        type: User
+
+  - name: changed-reviewers-remove
+    reviewers:
+      - id: 1
+        type: Team
+
+  - name: changed-reviewers-add
+    reviewers:
+      - id: 1
+        type: Team
+      - id: 2
+        type: User
+      - id: 3
+        type: User
+
+  - name: changed-deployment-branch-policy
+    deployment_branch_policy:
+      custom_branches:
+        - stage/*
+        - uat/*
+
+  - name: changed-all
+    wait_timer: 10
+    reviewers:
+      - id: 2
+        type: User
+    deployment_branch_policy:
+      custom_branches:
+        - dev/*
+
+  - name: new-environment
+    wait_timer: 1
+    reviewers:
+      - id: 1
+        type: Team
+      - id: 2
+        type: User
+    deployment_branch_policy:
+      protected_branches: true
+
+  - name: unchanged-default-wait-timer
+
+  - name: unchanged-wait-timer
+    wait_timer: 1
+
+  - name: unchanged-reviewers-unsorted
+    reviewers:
+      - id: 2
+        type: User
+      - id: 1
+        type: Team
+
+  - name: unchanged-reviewers-sorted
+    reviewers:
+      - id: 1
+        type: Team
+      - id: 2
+        type: User
+
+  - name: unchanged-deployment-branch-policy
+    deployment_branch_policy:
+      custom_branches:
+        - dev/*
+        - dev-*
diff --git a/test/integration/plugins/environments.test.js b/test/integration/plugins/environments.test.js
new file mode 100644
index 0000000000..b0f23a7fb7
--- /dev/null
+++ b/test/integration/plugins/environments.test.js
@@ -0,0 +1,211 @@
+const path = require('path')
+const fs = require('fs')
+const { CREATED, NO_CONTENT, OK } = require('http-status-codes')
+const settings = require('../../../lib/settings')
+const { buildTriggerEvent, initializeNock, loadInstance, repository, teardownNock } = require('../common')
+
+describe('environments plugin', function () {
+  let probot, githubScope
+
+  beforeEach(async () => {
+    githubScope = initializeNock()
+    probot = await loadInstance()
+  })
+
+  afterEach(() => {
+    teardownNock(githubScope)
+  })
+
+  it('syncs environments', async () => {
+    const pathToConfig = path.resolve(__dirname, '..', '..', 'fixtures', 'environments-config.yml')
+    const configFile = Buffer.from(fs.readFileSync(pathToConfig, 'utf8'))
+    const config = configFile.toString()
+    githubScope
+      .get(`/repos/${repository.owner.name}/${repository.name}/contents/${encodeURIComponent(settings.FILE_NAME)}`)
+      .reply(OK, config)
+    githubScope.get(`/repos/${repository.owner.name}/${repository.name}/environments`).reply(OK, {
+      environments: [
+        { name: 'changed-wait-timer', wait_timer: 1 },
+        {
+          name: 'changed-reviewers-type',
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'changed-reviewers-id',
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'changed-reviewers-remove',
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'changed-reviewers-add',
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'changed-deployment-branch-policy',
+          deployment_branch_policy: { protected_branches: true, custom_branch_policies: false }
+        },
+        { name: 'changed-all', wait_timer: 0 },
+        { name: 'unchanged-default-wait-timer', wait_timer: 0 },
+        { name: 'unchanged-wait-timer', wait_timer: 1 },
+        {
+          name: 'unchanged-reviewers-unsorted',
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'unchanged-reviewers-sorted',
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'unchanged-deployment-branch-policy',
+          deployment_branch_policy: { protected_branches: false, custom_branch_policies: true }
+        },
+        { name: 'deleted', wait_timer: 0 }
+      ]
+    })
+    githubScope
+      .get(
+        `/repos/${repository.owner.name}/${repository.name}/environments/unchanged-deployment-branch-policy/deployment-branch-policies`
+      )
+      .reply(OK, {
+        branch_policies: [
+          {
+            id: 1,
+            node_id: '1',
+            name: 'dev/*'
+          },
+          {
+            id: 2,
+            node_id: '2',
+            name: 'dev-*'
+          }
+        ]
+      })
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-wait-timer`, body => {
+        expect(body).toMatchObject({ wait_timer: 10 })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-reviewers-type`, body => {
+        expect(body).toMatchObject({
+          reviewers: [
+            { id: 1, type: 'User' },
+            { id: 2, type: 'User' }
+          ]
+        })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-reviewers-id`, body => {
+        expect(body).toMatchObject({
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 3, type: 'User' }
+          ]
+        })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-reviewers-remove`, body => {
+        expect(body).toMatchObject({ reviewers: [{ id: 1, type: 'Team' }] })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-reviewers-add`, body => {
+        expect(body).toMatchObject({
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' },
+            { id: 3, type: 'User' }
+          ]
+        })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-deployment-branch-policy`, body => {
+        expect(body).toMatchObject({
+          deployment_branch_policy: { protected_branches: false, custom_branch_policies: true }
+        })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .post(
+        `/repos/${repository.owner.name}/${repository.name}/environments/changed-deployment-branch-policy/deployment-branch-policies`,
+        body => {
+          expect(body).toMatchObject({ name: 'stage/*' })
+          return true
+        }
+      )
+      .reply(OK, { id: 3, node_id: '3', name: 'stage/*' })
+    githubScope
+      .post(
+        `/repos/${repository.owner.name}/${repository.name}/environments/changed-deployment-branch-policy/deployment-branch-policies`,
+        body => {
+          expect(body).toMatchObject({ name: 'uat/*' })
+          return true
+        }
+      )
+      .reply(OK, { id: 4, node_id: '4', name: 'uat/*' })
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/changed-all`, body => {
+        expect(body).toMatchObject({
+          wait_timer: 10,
+          reviewers: [{ id: 2, type: 'User' }],
+          deployment_branch_policy: { protected_branches: false, custom_branch_policies: true }
+        })
+        return true
+      })
+      .reply(CREATED)
+    githubScope
+      .post(
+        `/repos/${repository.owner.name}/${repository.name}/environments/changed-all/deployment-branch-policies`,
+        body => {
+          expect(body).toMatchObject({ name: 'dev/*' })
+          return true
+        }
+      )
+      .reply(OK, { id: 5, node_id: '5', name: 'dev/*' })
+    githubScope
+      .put(`/repos/${repository.owner.name}/${repository.name}/environments/new-environment`, body => {
+        expect(body).toMatchObject({
+          wait_timer: 1,
+          reviewers: [
+            { id: 1, type: 'Team' },
+            { id: 2, type: 'User' }
+          ],
+          deployment_branch_policy: { protected_branches: true, custom_branch_policies: false }
+        })
+        return true
+      })
+      .reply(CREATED)
+    githubScope.delete(`/repos/${repository.owner.name}/${repository.name}/environments/deleted`).reply(NO_CONTENT)
+
+    await probot.receive(buildTriggerEvent())
+  })
+})
diff --git a/test/unit/lib/plugins/environments.test.js b/test/unit/lib/plugins/environments.test.js
new file mode 100644
index 0000000000..bf399e9b49
--- /dev/null
+++ b/test/unit/lib/plugins/environments.test.js
@@ -0,0 +1,226 @@
+const { when } = require('jest-when')
+const Environments = require('../../../../lib/plugins/environments')
+
+describe('Environments', () => {
+  let github
+  const org = 'bkeepers'
+  const repo = 'test'
+
+  function configure (config) {
+    return new Environments(github, { owner: org, repo }, config)
+  }
+
+  beforeEach(() => {
+    github = {
+      request: jest.fn().mockReturnValue(Promise.resolve(true))
+    }
+  })
+
+  describe('sync', () => {
+    it('syncs environments', () => {
+      const plugin = configure([
+        { name: 'changed-wait-timer', wait_timer: 10 },
+        {
+          name: 'changed-reviewers-type',
+          reviewers: [
+            { id: 1, type: 'User' },
+            { id: 2, type: 'User' }
+          ]
+        },
+        {
+          name: 'new-environment',
+          wait_timer: 1,
+          reviewers: [
+            {
+              id: 1,
+              type: 'Team'
+            },
+            {
+              id: 2,
+              type: 'User'
+            }
+          ],
+          deployment_branch_policy: {
+            custom_branches: ['dev/*', 'dev-*']
+          }
+        },
+        {
+          name: 'changed-branch-policy',
+          deployment_branch_policy: {
+            protected_branches: true
+          }
+        },
+        {
+          name: 'unchanged-reviewers-unsorted',
+          reviewers: [
+            {
+              id: 2,
+              type: 'User'
+            },
+            {
+              id: 1,
+              type: 'Team'
+            }
+          ]
+        },
+        { name: 'Different-case', wait_timer: 0 }
+      ])
+
+      when(github.request)
+        .calledWith('GET /repos/:org/:repo/environments', { org, repo })
+        .mockResolvedValue({
+          data: {
+            environments: [
+              { name: 'different-Case', wait_timer: 0 },
+              { name: 'changed-wait-timer', wait_timer: 0 },
+              {
+                name: 'changed-reviewers-type',
+                reviewers: [
+                  { id: 1, type: 'Team' },
+                  { id: 2, type: 'User' }
+                ]
+              },
+              {
+                name: 'changed-branch-policy',
+                deployment_branch_policy: {
+                  protected_branches: false,
+                  custom_branch_policies: true
+                }
+              },
+              {
+                name: 'unchanged-reviewers-unsorted',
+                reviewers: [
+                  { id: 1, type: 'Team' },
+                  { id: 2, type: 'User' }
+                ]
+              },
+              { name: 'deleted', wait_timer: 0 }
+            ]
+          }
+        })
+
+      when(github.request)
+        .calledWith('GET /repos/:org/:repo/environments/:environment_name/deployment-branch-policies', {
+          org,
+          repo,
+          environment_name: 'changed-branch-policy'
+        })
+        .mockResolvedValue({
+          data: {
+            branch_policies: [
+              {
+                id: 2,
+                node_id: '2',
+                name: 'dev-*'
+              },
+              {
+                id: 1,
+                node_id: '1',
+                name: 'dev/*'
+              }
+            ]
+          }
+        })
+
+      return plugin.sync().then(() => {
+        expect(github.request).toHaveBeenCalledWith('PUT /repos/:org/:repo/environments/:environment_name', {
+          org,
+          repo,
+          environment_name: 'changed-wait-timer',
+          deployment_branch_policy: null,
+          wait_timer: 10
+        })
+
+        expect(github.request).toHaveBeenCalledWith('PUT /repos/:org/:repo/environments/:environment_name', {
+          org,
+          repo,
+          environment_name: 'changed-reviewers-type',
+          deployment_branch_policy: null,
+          wait_timer: 0,
+          reviewers: [
+            { id: 1, type: 'User' },
+            { id: 2, type: 'User' }
+          ]
+        })
+
+        expect(github.request).toHaveBeenCalledWith('PUT /repos/:org/:repo/environments/:environment_name', {
+          org,
+          repo,
+          environment_name: 'new-environment',
+          wait_timer: 1,
+          reviewers: [
+            {
+              id: 1,
+              type: 'Team'
+            },
+            {
+              id: 2,
+              type: 'User'
+            }
+          ],
+          deployment_branch_policy: {
+            protected_branches: false,
+            custom_branch_policies: true
+          }
+        })
+
+        expect(github.request).toHaveBeenCalledWith(
+          'POST /repos/:org/:repo/environments/:environment_name/deployment-branch-policies',
+          {
+            org,
+            repo,
+            environment_name: 'new-environment',
+            name: 'dev/*'
+          }
+        )
+
+        expect(github.request).toHaveBeenCalledWith(
+          'POST /repos/:org/:repo/environments/:environment_name/deployment-branch-policies',
+          {
+            org,
+            repo,
+            environment_name: 'new-environment',
+            name: 'dev-*'
+          }
+        )
+
+        expect(github.request).toHaveBeenCalledWith(
+          'DELETE /repos/:org/:repo/environments/:environment_name/deployment-branch-policies/:id',
+          {
+            org,
+            repo,
+            environment_name: 'changed-branch-policy',
+            id: 1
+          }
+        )
+
+        expect(github.request).toHaveBeenCalledWith(
+          'DELETE /repos/:org/:repo/environments/:environment_name/deployment-branch-policies/:id',
+          {
+            org,
+            repo,
+            environment_name: 'changed-branch-policy',
+            id: 2
+          }
+        )
+
+        expect(github.request).toHaveBeenCalledWith('PUT /repos/:org/:repo/environments/:environment_name', {
+          org,
+          repo,
+          environment_name: 'changed-branch-policy',
+          wait_timer: 0,
+          deployment_branch_policy: {
+            protected_branches: true,
+            custom_branch_policies: false
+          }
+        })
+
+        expect(github.request).toHaveBeenCalledWith('DELETE /repos/:org/:repo/environments/:environment_name', {
+          org,
+          repo,
+          environment_name: 'deleted'
+        })
+      })
+    })
+  })
+})