diff --git a/CHANGES.md b/CHANGES.md
index cfb0155f895..e66656b35f4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -15,6 +15,10 @@
   - `TrackingReferenceFrame.VELOCITY`: uses entity's `VelocityOrientationProperty` as orientation.
 - Added `GoogleGeocoderService` for standalone usage of Google geocoder. [#12299](https://github.com/CesiumGS/cesium/pull/12299)
 
+##### Breaking Changes :mega:
+
+- `Rectangle.validate` has been removed.
+
 ##### Fixes :wrench:
 
 - Fix label rendering bug in WebGL1 contexts. [#12301](https://github.com/CesiumGS/cesium/pull/12301)
diff --git a/packages/engine/Source/Core/Rectangle.js b/packages/engine/Source/Core/Rectangle.js
index 915a5289f90..70cd68fafaa 100644
--- a/packages/engine/Source/Core/Rectangle.js
+++ b/packages/engine/Source/Core/Rectangle.js
@@ -7,7 +7,6 @@ import Ellipsoid from "./Ellipsoid.js";
 import CesiumMath from "./Math.js";
 import Transforms from "./Transforms.js";
 import Matrix4 from "./Matrix4.js";
-import deprecationWarning from "./deprecationWarning.js";
 
 /**
  * A two dimensional region specified as longitude and latitude coordinates.
@@ -533,25 +532,6 @@ Rectangle.prototype.equalsEpsilon = function (other, epsilon) {
   return Rectangle.equalsEpsilon(this, other, epsilon);
 };
 
-/**
- * Checks a Rectangle's properties and throws if they are not in valid ranges.
- *
- * @param {Rectangle} rectangle The rectangle to validate
- *
- * @exception {DeveloperError} <code>north</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
- * @exception {DeveloperError} <code>south</code> must be in the interval [<code>-Pi/2</code>, <code>Pi/2</code>].
- * @exception {DeveloperError} <code>east</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
- * @exception {DeveloperError} <code>west</code> must be in the interval [<code>-Pi</code>, <code>Pi</code>].
- * @deprecated This function is deprecated and will be removed in Cesium 1.124. See <a href="https://github.com/CesiumGS/cesium/issues/4921">Issue 4921</a>
- */
-Rectangle.validate = function (rectangle) {
-  deprecationWarning(
-    "Rectangle.validate",
-    "Rectangle.validate is a no-op and has been deprecated. It will be removed in Cesium 1.124.",
-  );
-  return Rectangle._validate(rectangle);
-};
-
 /**
  * Checks a Rectangle's properties and throws if they are not in valid ranges.
  *