diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d3ba84ed84..4119ac01e96 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## Master
 
+* Fix ComputeRMSE bug when ColoredICP.
 * Fix tensor based TSDF integration example.
 * Use GLIBCXX_USE_CXX11_ABI=ON by default
 * Python 3.9 support. Tensorflow bump 2.4.1 -> 2.5.0. PyTorch bump 1.7.1 -> 1.8.1 (LTS)
diff --git a/cpp/open3d/pipelines/registration/ColoredICP.cpp b/cpp/open3d/pipelines/registration/ColoredICP.cpp
index 0365e3dc662..25339315370 100644
--- a/cpp/open3d/pipelines/registration/ColoredICP.cpp
+++ b/cpp/open3d/pipelines/registration/ColoredICP.cpp
@@ -208,7 +208,7 @@ double TransformationEstimationForColoredICP::ComputeRMSE(
         residual += residual_geometric * residual_geometric +
                     residual_photometric * residual_photometric;
     }
-    return residual;
+    return std::sqrt(residual / (double)corres.size());
 };
 
 RegistrationResult RegistrationColoredICP(