diff --git a/packages/block-library/src/comments/block.json b/packages/block-library/src/comments/block.json
index b35ea3505c816f..cbdf5b3725b84b 100644
--- a/packages/block-library/src/comments/block.json
+++ b/packages/block-library/src/comments/block.json
@@ -17,7 +17,10 @@
 		}
 	},
 	"supports": {
-		"align": [ "wide", "full" ],
+		"align": [
+			"wide",
+			"full"
+		],
 		"html": false,
 		"color": {
 			"gradients": true,
@@ -45,8 +48,23 @@
 			"__experimentalDefaultControls": {
 				"fontSize": true
 			}
+		},
+		"__experimentalBorder": {
+			"radius": true,
+			"color": true,
+			"width": true,
+			"style": true,
+			"__experimentalDefaultControls": {
+				"radius": true,
+				"color": true,
+				"width": true,
+				"style": true
+			}
 		}
 	},
 	"editorStyle": "wp-block-comments-editor",
-	"usesContext": [ "postId", "postType" ]
-}
+	"usesContext": [
+		"postId",
+		"postType"
+	]
+}
\ No newline at end of file
diff --git a/packages/block-library/src/comments/style.scss b/packages/block-library/src/comments/style.scss
index be8cf1e597f49f..081783db098ab1 100644
--- a/packages/block-library/src/comments/style.scss
+++ b/packages/block-library/src/comments/style.scss
@@ -13,7 +13,6 @@
 	}
 
 	/* end utility classes */
-
 	.navigation {
 		&::after {
 			content: "";
@@ -146,3 +145,7 @@
 :where(.wp-block-post-comments input[type="submit"]) {
 	border: none;
 }
+
+.wp-block-comments {
+	box-sizing: border-box;
+}