diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index bd5513a..a20c99a 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -26,6 +26,7 @@ jobs:
           - { ruby: '2.7.1', mongo: 'mongo:4.4', mongoid: '8' }
           - { ruby: '3.0.5', mongo: 'mongo:4.4', mongoid: '8' }
           - { ruby: '3.1.3', mongo: 'mongo:4.4', mongoid: '8' }
+          - { ruby: '3.1.3', mongo: 'mongo:4.4', mongoid: '9' }
         experimental: [false]
 
     name: test (ruby=${{ matrix.entry.ruby }}, mongo=${{ matrix.entry.mongo }}, mongoid=${{ matrix.entry.mongoid }})
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ccb8115..f5a7353 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,10 +1,10 @@
 ## Changelog
 
-### 2.0.3 (Next)
-
+### 2.1.0 (Next)
+* [#101](https://github.com/mongoid/mongoid-locker/pull/101): Replace the $where operator with the $expr operator - [@amanfrinati](https://github.com/amanfrinati).
 * [#102](https://github.com/mongoid/mongoid-locker/pull/102): Re-added danger, removed Travis-CI config, extracted RuboCop - [@dblock](https://github.com/dblock).
 * [#104](https://github.com/mongoid/mongoid-locker/pull/104): Fixed code coverage - [@dblock](https://github.com/dblock).
-* [#101](https://github.com/mongoid/mongoid-locker/pull/101): Replace the $where operator with the $expr operator - [@amanfrinati](https://github.com/amanfrinati).
+* [#105](https://github.com/mongoid/mongoid-locker/pull/105): Added support for Mongoid 9.0 - [@saisrinivasan](https://github.com/SairamSrinivasan).
 * Your contribution here.
 
 ### 2.0.2 (2023-01-24)
diff --git a/Gemfile b/Gemfile
index c100811..1d8e285 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,6 +4,8 @@ source 'https://rubygems.org'
 gemspec
 
 case ENV['MONGOID_VERSION']
+when /^9/
+  gem 'mongoid', '~> 9.0'
 when /^8/
   gem 'mongoid', '~> 8.0'
 when /^7/
diff --git a/README.md b/README.md
index e1dc22d..fd265bb 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ Document-level optimistic locking for MongoDB via Mongoid. Mongoid-Locker is an
 [Tested](https://github.com/mongoid/mongoid-locker/actions) against:
 - MRI: `2.3.8`, `2.4.7`, `2.5.7`, `2.6.6`, `2.7.1`, `3.0.5`, `3.1.3`
 - JRuby `9.1.17.0`, `9.2.11.1`
-- Mongoid: `5`, `6`, `7`, `8`
+- Mongoid: `5`, `6`, `7`, `8`, '9'
 
 See [.github/workflows/test.yml](.github/workflows/test.yml) for the latest test matrix.
 
diff --git a/mongoid-locker.gemspec b/mongoid-locker.gemspec
index c7d7f56..bdcfdcc 100644
--- a/mongoid-locker.gemspec
+++ b/mongoid-locker.gemspec
@@ -18,5 +18,5 @@ Gem::Specification.new do |s|
   s.files = `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(spec)/}) }
   s.require_paths = ['lib']
 
-  s.add_dependency 'mongoid', '>= 5.0', '< 9'
+  s.add_dependency 'mongoid', '>= 5.0', '< 10'
 end