diff --git a/Octokit.Reactive/Clients/IObservableOrganizationMembersClient.cs b/Octokit.Reactive/Clients/IObservableOrganizationMembersClient.cs
index 4c80d17f..8e5a903b 100644
--- a/Octokit.Reactive/Clients/IObservableOrganizationMembersClient.cs
+++ b/Octokit.Reactive/Clients/IObservableOrganizationMembersClient.cs
@@ -363,7 +363,19 @@ namespace Octokit.Reactive
         /// <param name="options">Options to change API behaviour</param>
         /// <returns></returns>
         IObservable<OrganizationMembershipInvitation> GetAllFailedInvitations(string org, ApiOptions options);
-        
+
+        /// <summary>
+        /// Cancel an organization invitation. In order to cancel an organization invitation, the authenticated user must be an organization owner.
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="https://docs.github.com/en/rest/orgs/members#cancel-an-organization-invitation">API Documentation</a>
+        /// for more information.
+        /// </remarks>
+        /// <param name="org">The login for the organization</param>
+        /// <param name="invitationId">The unique identifier of the invitation</param>
+        /// <returns></returns>
+        IObservable<Unit> CancelOrganizationInvitation(string org, int invitationId);
+
         /// <summary>
         /// Returns all <see cref="OrganizationMembership" />s for the current user.
         /// </summary>
diff --git a/Octokit.Reactive/Clients/ObservableOrganizationMembersClient.cs b/Octokit.Reactive/Clients/ObservableOrganizationMembersClient.cs
index f7616aac..e258722c 100644
--- a/Octokit.Reactive/Clients/ObservableOrganizationMembersClient.cs
+++ b/Octokit.Reactive/Clients/ObservableOrganizationMembersClient.cs
@@ -507,6 +507,25 @@ namespace Octokit.Reactive
             return _connection.GetAndFlattenAllPages<OrganizationMembershipInvitation>(ApiUrls.OrganizationFailedInvitations(org), null, options);
         }
 
+        /// <summary>
+        /// Cancel an organization invitation. In order to cancel an organization invitation, the authenticated user must be an organization owner.
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="https://docs.github.com/en/rest/orgs/members#cancel-an-organization-invitation">API Documentation</a>
+        /// for more information.
+        /// </remarks>
+        /// <param name="org">The login for the organization</param>
+        /// <param name="invitationId">The unique identifier of the invitation</param>
+        /// <returns></returns>
+        [ManualRoute("DELETE", "/orgs/{org}/invitations/{invitation_id}")]
+        public IObservable<Unit> CancelOrganizationInvitation(string org, int invitationId)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(org, nameof(org));
+            Ensure.ArgumentNotNullOrDefault(invitationId, nameof(invitationId));
+
+            return _client.CancelOrganizationInvitation(org, invitationId).ToObservable();
+        }
+
         /// <summary>
         /// Returns all <see cref="OrganizationMembership" />s for the current user.
         /// </summary>
diff --git a/Octokit.Tests/Clients/OrganizationMembersClientTests.cs b/Octokit.Tests/Clients/OrganizationMembersClientTests.cs
index e920dcb2..d09ed836 100644
--- a/Octokit.Tests/Clients/OrganizationMembersClientTests.cs
+++ b/Octokit.Tests/Clients/OrganizationMembersClientTests.cs
@@ -628,5 +628,29 @@ namespace Octokit.Tests.Clients
                 await Assert.ThrowsAsync<ArgumentNullException>(() => client.GetAllPendingInvitations("org", null));
             }
         }
+
+        public class TheCancelOrganizationInvitationMethod
+        {
+            [Fact]
+            public void PostsToCorrectUrl()
+            {
+                var connection = Substitute.For<IApiConnection>();
+                var client = new OrganizationMembersClient(connection);
+
+                client.CancelOrganizationInvitation("org", 1);
+
+                connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "orgs/org/invitations/1"));
+            }
+
+            [Fact]
+            public async Task EnsureNonNullArguments()
+            {
+                var client = new OrganizationMembersClient(Substitute.For<IApiConnection>());
+
+                await Assert.ThrowsAsync<ArgumentNullException>(() => client.CancelOrganizationInvitation(null, 1));
+                await Assert.ThrowsAsync<ArgumentException>(() => client.CancelOrganizationInvitation("", 1));
+                await Assert.ThrowsAsync<ArgumentNullException>(() => client.CancelOrganizationInvitation("org", 0));
+            }
+        }
     }
 }
diff --git a/Octokit.Tests/Reactive/ObservableOrganizationMembersClientTests.cs b/Octokit.Tests/Reactive/ObservableOrganizationMembersClientTests.cs
index b06b3f9e..6e3e44b4 100644
--- a/Octokit.Tests/Reactive/ObservableOrganizationMembersClientTests.cs
+++ b/Octokit.Tests/Reactive/ObservableOrganizationMembersClientTests.cs
@@ -434,5 +434,29 @@ namespace Octokit.Tests.Reactive
                 await Assert.ThrowsAsync<ArgumentNullException>(() => client.GetAllPendingInvitations("org", null).ToTask());
             }
         }
+
+        public class TheCancelOrganizationInvitationMethod
+        {
+            [Fact]
+            public void CancelInvitationFromClientOrganizationMember()
+            {
+                var gitHubClient = Substitute.For<IGitHubClient>();
+                var client = new ObservableOrganizationMembersClient(gitHubClient);
+
+                client.CancelOrganizationInvitation("org", 1);
+
+                gitHubClient.Organization.Member.Received().CancelOrganizationInvitation("org", 1);
+            }
+
+            [Fact]
+            public async Task EnsuresNonNullArguments()
+            {
+                var client = new ObservableOrganizationMembersClient(Substitute.For<IGitHubClient>());
+
+                await Assert.ThrowsAsync<ArgumentNullException>(() => client.CancelOrganizationInvitation(null, 1).ToTask());
+                await Assert.ThrowsAsync<ArgumentException>(() => client.CancelOrganizationInvitation("", 1).ToTask());
+                await Assert.ThrowsAsync<ArgumentNullException>(() => client.CancelOrganizationInvitation("org", 0).ToTask());
+            }
+        }
     }
 }
diff --git a/Octokit/Clients/IOrganizationMembersClient.cs b/Octokit/Clients/IOrganizationMembersClient.cs
index 222e10e5..c16707f9 100644
--- a/Octokit/Clients/IOrganizationMembersClient.cs
+++ b/Octokit/Clients/IOrganizationMembersClient.cs
@@ -370,6 +370,18 @@ namespace Octokit
         /// <returns></returns>
         Task<IReadOnlyList<OrganizationMembershipInvitation>> GetAllFailedInvitations(string org, ApiOptions options);
 
+        /// <summary>
+        /// Cancel an organization invitation. In order to cancel an organization invitation, the authenticated user must be an organization owner.
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="https://docs.github.com/en/rest/orgs/members#cancel-an-organization-invitation">API Documentation</a>
+        /// for more information.
+        /// </remarks>
+        /// <param name="org">The login for the organization</param>
+        /// <param name="invitationId">The unique identifier of the invitation</param>
+        /// <returns></returns>
+        Task CancelOrganizationInvitation(string org, int invitationId);
+
         /// <summary>
         /// Returns all <see cref="OrganizationMembership" />s for the current user.
         /// </summary>
diff --git a/Octokit/Clients/OrganizationMembersClient.cs b/Octokit/Clients/OrganizationMembersClient.cs
index 2e2de872..b5fd87de 100644
--- a/Octokit/Clients/OrganizationMembersClient.cs
+++ b/Octokit/Clients/OrganizationMembersClient.cs
@@ -604,6 +604,25 @@ namespace Octokit
             return ApiConnection.GetAll<OrganizationMembershipInvitation>(ApiUrls.OrganizationFailedInvitations(org), null, options);
         }
 
+        /// <summary>
+        /// Cancel an organization invitation. In order to cancel an organization invitation, the authenticated user must be an organization owner.
+        /// </summary>
+        /// <remarks>
+        /// See the <a href="https://docs.github.com/en/rest/orgs/members#cancel-an-organization-invitation">API Documentation</a>
+        /// for more information.
+        /// </remarks>
+        /// <param name="org">The login for the organization</param>
+        /// <param name="invitationId">The unique identifier of the invitation</param>
+        /// <returns></returns>
+        [ManualRoute("DELETE", "/orgs/{org}/invitations/{invitation_id}")]
+        public Task CancelOrganizationInvitation(string org, int invitationId)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(org, nameof(org));
+            Ensure.ArgumentNotNullOrDefault(invitationId, nameof(invitationId));
+
+            return ApiConnection.Delete(ApiUrls.CancelOrganizationInvitation(org, invitationId));
+        }
+
         /// <summary>
         /// Returns all <see cref="OrganizationMembership" />s for the current user.
         /// </summary>
diff --git a/Octokit/Helpers/ApiUrls.cs b/Octokit/Helpers/ApiUrls.cs
index 483df805..50b8e1a0 100644
--- a/Octokit/Helpers/ApiUrls.cs
+++ b/Octokit/Helpers/ApiUrls.cs
@@ -943,6 +943,17 @@ namespace Octokit
             return "orgs/{0}/failed_invitations".FormatUri(org);
         }
 
+        /// <summary>
+        /// Returns the <see cref="Uri"/> to cancel an organization invitation
+        /// </summary>
+        /// <param name="org">The name of the organization</param>
+        /// <param name="invitationId">The unique identifier of the invitation</param>
+        /// <returns></returns>
+        public static Uri CancelOrganizationInvitation(string org, int invitationId)
+        {
+            return "orgs/{0}/invitations/{1}".FormatUri(org, invitationId);
+        }
+
         /// <summary>
         /// Returns the <see cref="Uri"/> that returns all of the outside collaborators of the organization
         /// </summary>