diff --git a/CHANGELOG.md b/CHANGELOG.md
index ca9184d796..9c417fd6bf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ _This release is scheduled to be released on 2023-10-01._
 - Added AnimateIn and animateOut in module config definition
 - Apply AnimateIn rules on the first start
 - Added automatic client page reload when server was restarted by setting `reloadAfterServerRestart: true` in `config.js`, per default `false` (#3105)
+- Added eventClass option for customEvents on the default calendar
 
 ### Removed
 
diff --git a/modules/default/calendar/calendar.js b/modules/default/calendar/calendar.js
index 30f7baa226..681177d514 100644
--- a/modules/default/calendar/calendar.js
+++ b/modules/default/calendar/calendar.js
@@ -42,7 +42,7 @@ Module.register("calendar", {
 		hideDuplicates: true,
 		showTimeToday: false,
 		colored: false,
-		customEvents: [], // Array of {keyword: "", symbol: "", color: ""} where Keyword is a regexp and symbol/color are to be applied for matched
+		customEvents: [], // Array of {keyword: "", symbol: "", color: "", eventClass: ""} where Keyword is a regexp and symbol/color/eventClass are to be applied for matched
 		tableClass: "small",
 		calendars: [
 			{
@@ -321,12 +321,12 @@ Module.register("calendar", {
 				}
 			}
 
-			// Color events if custom color is specified
+			// Color events if custom color or eventClass are specified
 			if (this.config.customEvents.length > 0) {
 				for (let ev in this.config.customEvents) {
-					if (typeof this.config.customEvents[ev].color !== "undefined" && this.config.customEvents[ev].color !== "") {
-						let needle = new RegExp(this.config.customEvents[ev].keyword, "gi");
-						if (needle.test(event.title)) {
+					let needle = new RegExp(this.config.customEvents[ev].keyword, "gi");
+					if (needle.test(event.title)) {
+						if (typeof this.config.customEvents[ev].color !== "undefined" && this.config.customEvents[ev].color !== "") {
 							// Respect parameter ColoredSymbolOnly also for custom events
 							if (this.config.coloredText) {
 								eventWrapper.style.cssText = `color:${this.config.customEvents[ev].color}`;
@@ -337,6 +337,9 @@ Module.register("calendar", {
 							}
 							break;
 						}
+						if (typeof this.config.customEvents[ev].eventClass !== "undefined" && this.config.customEvents[ev].eventClass !== "") {
+							eventWrapper.className += ` ${this.config.customEvents[ev].eventClass}`;
+						}
 					}
 				}
 			}
diff --git a/tests/configs/modules/calendar/custom.js b/tests/configs/modules/calendar/custom.js
index 993ac483e6..4153da0460 100644
--- a/tests/configs/modules/calendar/custom.js
+++ b/tests/configs/modules/calendar/custom.js
@@ -11,7 +11,7 @@ let config = {
 			module: "calendar",
 			position: "bottom_bar",
 			config: {
-				customEvents: [{ keyword: "CustomEvent", symbol: "dice" }],
+				customEvents: [{ keyword: "CustomEvent", symbol: "dice", eventClass: "undo" }],
 				calendars: [
 					{
 						maximumEntries: 5,
diff --git a/tests/e2e/modules/calendar_spec.js b/tests/e2e/modules/calendar_spec.js
index fc9c1a174e..299bdf664e 100644
--- a/tests/e2e/modules/calendar_spec.js
+++ b/tests/e2e/modules/calendar_spec.js
@@ -60,6 +60,10 @@ describe("Calendar module", () => {
 			await testElementLength(".calendar .event .fa-dice", 1);
 		});
 
+		it("should show a customEvent calendar eventClass in one event", async () => {
+			await testElementLength(".calendar .event.undo", 1);
+		});
+
 		it("should show two custom icons for repeating events", async () => {
 			await testElementLength(".calendar .event .fa-undo", 2);
 		});