diff --git a/.changes/next-release/documentation-AmazonS3-259552c.json b/.changes/next-release/documentation-AmazonS3-259552c.json
new file mode 100644
index 000000000000..00a7be6dc8ed
--- /dev/null
+++ b/.changes/next-release/documentation-AmazonS3-259552c.json
@@ -0,0 +1,6 @@
+{
+    "category": "Amazon S3", 
+    "contributor": "", 
+    "type": "documentation", 
+    "description": "Deprecate S3 CopySource parameter for CopyObject & UploadPartCopy"
+}
diff --git a/services/s3/src/main/resources/codegen-resources/customization.config b/services/s3/src/main/resources/codegen-resources/customization.config
index 1f2e50aa08b4..04413d672c4f 100644
--- a/services/s3/src/main/resources/codegen-resources/customization.config
+++ b/services/s3/src/main/resources/codegen-resources/customization.config
@@ -35,6 +35,10 @@
       ],
       "modify": [
         {
+          "CopySource": {
+            "deprecated": true,
+            "deprecatedMessage": "The {@code copySource} parameter has been deprecated in favor of the more user-friendly {@code sourceBucket}, {@code sourceKey}, and {@code sourceVersionId} parameters. The {@code copySource} parameter will remain fully functional, but it must not be used in conjunction with its replacement parameters."
+          },
           "Bucket": {
             "emitPropertyName": "DestinationBucket",
             "existingNameDeprecated": true
@@ -65,6 +69,10 @@
       ],
       "modify": [
         {
+          "CopySource": {
+            "deprecated": true,
+            "deprecatedMessage": "The {@code copySource} parameter has been deprecated in favor of the more user-friendly {@code sourceBucket}, {@code sourceKey}, and {@code sourceVersionId} parameters. The {@code copySource} parameter will remain fully functional, but it must not be used in conjunction with its replacement parameters."
+          },
           "Bucket": {
             "emitPropertyName": "DestinationBucket",
             "existingNameDeprecated": true