diff --git a/github/dependabot_alerts.go b/github/dependabot_alerts.go
index 177316b1dc..9ea1f0396a 100644
--- a/github/dependabot_alerts.go
+++ b/github/dependabot_alerts.go
@@ -67,6 +67,17 @@ type DependabotAlert struct {
 	Repository *Repository `json:"repository,omitempty"`
 }
 
+// DependabotAlertState represents the state of a Dependabot alert to update.
+type DependabotAlertState struct {
+	// The state of the Dependabot alert. A dismissed_reason must be provided when setting the state to dismissed.
+	State string `json:"state"`
+	// Required when state is dismissed. A reason for dismissing the alert.
+	// Can be one of: fix_started, inaccurate, no_bandwidth, not_used, tolerable_risk
+	DismissedReason *string `json:"dismissed_reason,omitempty"`
+	// An optional comment associated with dismissing the alert.
+	DismissedComment *string `json:"dismissed_comment,omitempty"`
+}
+
 // ListAlertsOptions specifies the optional parameters to the DependabotService.ListRepoAlerts
 // and DependabotService.ListOrgAlerts methods.
 type ListAlertsOptions struct {
@@ -136,3 +147,22 @@ func (s *DependabotService) GetRepoAlert(ctx context.Context, owner, repo string
 
 	return alert, resp, nil
 }
+
+// UpdateAlert updates a Dependabot alert.
+//
+// GitHub API docs: https://docs.github.com/en/rest/dependabot/alerts?apiVersion=2022-11-28#update-a-dependabot-alert
+func (s *DependabotService) UpdateAlert(ctx context.Context, owner, repo string, number int, stateInfo *DependabotAlertState) (*DependabotAlert, *Response, error) {
+	url := fmt.Sprintf("repos/%v/%v/dependabot/alerts/%v", owner, repo, number)
+	req, err := s.client.NewRequest("PATCH", url, stateInfo)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	alert := new(DependabotAlert)
+	resp, err := s.client.Do(ctx, req, alert)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return alert, resp, nil
+}
diff --git a/github/dependabot_alerts_test.go b/github/dependabot_alerts_test.go
index a7c3b14788..45fd11ee41 100644
--- a/github/dependabot_alerts_test.go
+++ b/github/dependabot_alerts_test.go
@@ -131,3 +131,49 @@ func TestDependabotService_ListOrgAlerts(t *testing.T) {
 		return resp, err
 	})
 }
+
+func TestDependabotService_UpdateAlert(t *testing.T) {
+	client, mux, _, teardown := setup()
+	defer teardown()
+
+	state := String("dismissed")
+	dismissedReason := String("no_bandwidth")
+	dismissedComment := String("no time to fix this")
+
+	alertState := &DependabotAlertState{State: *state, DismissedReason: dismissedReason, DismissedComment: dismissedComment}
+
+	mux.HandleFunc("/repos/o/r/dependabot/alerts/42", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "PATCH")
+		fmt.Fprint(w, `{"number":42,"state":"dismissed","dismissed_reason":"no_bandwidth","dismissed_comment":"no time to fix this"}`)
+	})
+
+	ctx := context.Background()
+	alert, _, err := client.Dependabot.UpdateAlert(ctx, "o", "r", 42, alertState)
+	if err != nil {
+		t.Errorf("Dependabot.UpdateAlert returned error: %v", err)
+	}
+
+	want := &DependabotAlert{
+		Number:           Int(42),
+		State:            String("dismissed"),
+		DismissedReason:  String("no_bandwidth"),
+		DismissedComment: String("no time to fix this"),
+	}
+	if !cmp.Equal(alert, want) {
+		t.Errorf("Dependabot.UpdateAlert returned %+v, want %+v", alert, want)
+	}
+
+	const methodName = "UpdateAlert"
+	testBadOptions(t, methodName, func() (err error) {
+		_, _, err = client.Dependabot.UpdateAlert(ctx, "\n", "\n", 0, alertState)
+		return err
+	})
+
+	testNewRequestAndDoFailure(t, methodName, client, func() (*Response, error) {
+		got, resp, err := client.Dependabot.UpdateAlert(ctx, "o", "r", 42, alertState)
+		if got != nil {
+			t.Errorf("testNewRequestAndDoFailure %v = %#v, want nil", methodName, got)
+		}
+		return resp, err
+	})
+}