diff --git a/src/Octokit.Webhooks/Events/PullRequest/PullRequestAction.cs b/src/Octokit.Webhooks/Events/PullRequest/PullRequestAction.cs
index bd629d97..0f91b476 100644
--- a/src/Octokit.Webhooks/Events/PullRequest/PullRequestAction.cs
+++ b/src/Octokit.Webhooks/Events/PullRequest/PullRequestAction.cs
@@ -15,12 +15,16 @@ public sealed record PullRequestAction : WebhookEventAction
 
     public static readonly PullRequestAction Dequeued = new(PullRequestActionValue.Dequeued);
 
+    public static readonly PullRequestAction Demilestoned = new(PullRequestActionValue.Demilestoned);
+
     public static readonly PullRequestAction Edited = new(PullRequestActionValue.Edited);
 
     public static readonly PullRequestAction Labeled = new(PullRequestActionValue.Labeled);
 
     public static readonly PullRequestAction Locked = new(PullRequestActionValue.Locked);
 
+    public static readonly PullRequestAction Milestoned = new(PullRequestActionValue.Milestoned);
+
     public static readonly PullRequestAction Opened = new(PullRequestActionValue.Opened);
 
     public static readonly PullRequestAction Queued = new(PullRequestActionValue.Queued);
diff --git a/src/Octokit.Webhooks/Events/PullRequest/PullRequestActionValue.cs b/src/Octokit.Webhooks/Events/PullRequest/PullRequestActionValue.cs
index 1f7cced0..2756f41c 100644
--- a/src/Octokit.Webhooks/Events/PullRequest/PullRequestActionValue.cs
+++ b/src/Octokit.Webhooks/Events/PullRequest/PullRequestActionValue.cs
@@ -12,6 +12,8 @@ public static class PullRequestActionValue
 
     public const string ConvertedToDraft = "converted_to_draft";
 
+    public const string Demilestoned = "demilestoned";
+
     public const string Dequeued = "dequeued";
 
     public const string Edited = "edited";
@@ -20,6 +22,8 @@ public static class PullRequestActionValue
 
     public const string Locked = "locked";
 
+    public const string Milestoned = "milestoned";
+
     public const string Opened = "opened";
 
     public const string Queued = "queued";
diff --git a/src/Octokit.Webhooks/Events/PullRequest/PullRequestDemilestoned.cs b/src/Octokit.Webhooks/Events/PullRequest/PullRequestDemilestoned.cs
new file mode 100644
index 00000000..d1237973
--- /dev/null
+++ b/src/Octokit.Webhooks/Events/PullRequest/PullRequestDemilestoned.cs
@@ -0,0 +1,14 @@
+namespace Octokit.Webhooks.Events.PullRequest;
+
+using Milestone = Octokit.Webhooks.Models.Milestone;
+
+[PublicAPI]
+[WebhookActionType(PullRequestActionValue.Demilestoned)]
+public sealed record PullRequestDemilestoned : PullRequestEvent
+{
+    [JsonPropertyName("action")]
+    public override string Action => PullRequestAction.Demilestoned;
+
+    [JsonPropertyName("milestone")]
+    public Milestone Milestone { get; init; } = null!;
+}
diff --git a/src/Octokit.Webhooks/Events/PullRequest/PullRequestMilestoned.cs b/src/Octokit.Webhooks/Events/PullRequest/PullRequestMilestoned.cs
new file mode 100644
index 00000000..117d1333
--- /dev/null
+++ b/src/Octokit.Webhooks/Events/PullRequest/PullRequestMilestoned.cs
@@ -0,0 +1,14 @@
+namespace Octokit.Webhooks.Events.PullRequest;
+
+using Milestone = Octokit.Webhooks.Models.Milestone;
+
+[PublicAPI]
+[WebhookActionType(PullRequestActionValue.Milestoned)]
+public sealed record PullRequestMilestoned : PullRequestEvent
+{
+    [JsonPropertyName("action")]
+    public override string Action => PullRequestAction.Milestoned;
+
+    [JsonPropertyName("milestone")]
+    public Milestone Milestone { get; init; } = null!;
+}
diff --git a/src/Octokit.Webhooks/WebhookEventProcessor.cs b/src/Octokit.Webhooks/WebhookEventProcessor.cs
index bcd642ea..7c4c492c 100644
--- a/src/Octokit.Webhooks/WebhookEventProcessor.cs
+++ b/src/Octokit.Webhooks/WebhookEventProcessor.cs
@@ -789,9 +789,12 @@ private Task ProcessPullRequestWebhookAsync(WebhookHeaders headers, PullRequestE
                 => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.ConvertedToDraft),
             PullRequestActionValue.Dequeued =>
                 this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Dequeued),
+            PullRequestActionValue.Demilestoned =>
+                this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Demilestoned),
             PullRequestActionValue.Edited => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Edited),
             PullRequestActionValue.Labeled => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Labeled),
             PullRequestActionValue.Locked => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Locked),
+            PullRequestActionValue.Milestoned => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Milestoned),
             PullRequestActionValue.Opened => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Opened),
             PullRequestActionValue.Queued
                 => this.ProcessPullRequestWebhookAsync(headers, pullRequestEvent, PullRequestAction.Queued),