diff --git a/dts/arm/renesas/rz/rzg/r9a08g045.dtsi b/dts/arm/renesas/rz/rzg/r9a08g045.dtsi
index 084bd1267fb..6e1c33ba375 100644
--- a/dts/arm/renesas/rz/rzg/r9a08g045.dtsi
+++ b/dts/arm/renesas/rz/rzg/r9a08g045.dtsi
@@ -562,6 +562,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm1: gtm@42801400 {
 			compatible = "renesas,rz-gtm";
@@ -575,6 +580,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm2: gtm@42801800 {
 			compatible = "renesas,rz-gtm";
@@ -588,6 +598,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm3: gtm@42801c00 {
 			compatible = "renesas,rz-gtm";
@@ -601,6 +616,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm4: gtm@42802000 {
 			compatible = "renesas,rz-gtm";
@@ -614,6 +634,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm5: gtm@42802400 {
 			compatible = "renesas,rz-gtm";
@@ -627,6 +652,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm6: gtm@42802800 {
 			compatible = "renesas,rz-gtm";
@@ -640,6 +670,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 		gtm7: gtm@42802c00 {
 			compatible = "renesas,rz-gtm";
@@ -653,6 +688,11 @@
 				compatible = "renesas,rz-gtm-counter";
 				status = "disabled";
 			};
+
+			os_timer {
+				compatible = "renesas,rz-gtm-os-timer";
+				status = "disabled";
+			};
 		};
 
 		gpt32e0: gpt32e@50048000 {