diff --git a/.changeset/code-block-patch.md b/.changeset/code-block-patch.md
new file mode 100644
index 0000000000..ff009d5b0d
--- /dev/null
+++ b/.changeset/code-block-patch.md
@@ -0,0 +1,6 @@
+---
+'@platejs/code-block': patch
+---
+
+- Fixed normalizer using `setNodes` instead of `wrapNodes` for bare text children in `code_block`, which produced malformed `code_line` nodes (e.g. `{ text: "...", type: "code_line" }` instead of proper element structure). This caused syntax highlighting to only work on the first line.
+- Fixed `insertBreak` not resetting the decoration cache after splitting, so new lines now get syntax highlighting immediately.
diff --git a/packages/code-block/src/lib/withCodeBlock.ts b/packages/code-block/src/lib/withCodeBlock.ts
index e83cfa88af..9d700acffc 100644
--- a/packages/code-block/src/lib/withCodeBlock.ts
+++ b/packages/code-block/src/lib/withCodeBlock.ts
@@ -53,6 +53,9 @@ export const withCodeBlock: OverrideEditor<CodeBlockConfig> = (ctx) => {
             indentDepth,
           });
 
+          // Reset decoration cache so all lines get re-highlighted
+          resetCodeBlockDecorations(codeBlock[0] as TCodeBlockElement);
+
           return true;
         };
 
diff --git a/packages/code-block/src/lib/withNormalizeCodeBlock.tsx b/packages/code-block/src/lib/withNormalizeCodeBlock.tsx
index 665f32afd6..9a82ca129c 100644
--- a/packages/code-block/src/lib/withNormalizeCodeBlock.tsx
+++ b/packages/code-block/src/lib/withNormalizeCodeBlock.tsx
@@ -45,7 +45,13 @@ export const withNormalizeCodeBlock: OverrideEditor<CodeBlockConfig> = ({
         );
 
         if (nonCodeLine) {
-          editor.tf.setNodes({ type: codeLineType }, { at: nonCodeLine[1] });
+          // Use wrapNodes instead of setNodes to properly wrap bare text
+          // children in code_line elements (setNodes just adds a type
+          // property to text leaves, producing malformed nodes)
+          editor.tf.wrapNodes(
+            { type: codeLineType, children: [] },
+            { at: nonCodeLine[1] }
+          );
         }
       }
     },