diff --git a/extension-spring6/src/main/java/com/alibaba/fastjson2/support/spring6/http/converter/FastJsonHttpMessageConverter.java b/extension-spring6/src/main/java/com/alibaba/fastjson2/support/spring6/http/converter/FastJsonHttpMessageConverter.java
index a47344732d..4dd3d3b00b 100644
--- a/extension-spring6/src/main/java/com/alibaba/fastjson2/support/spring6/http/converter/FastJsonHttpMessageConverter.java
+++ b/extension-spring6/src/main/java/com/alibaba/fastjson2/support/spring6/http/converter/FastJsonHttpMessageConverter.java
@@ -126,6 +126,7 @@ protected void writeInternal(Object object, HttpOutputMessage outputMessage) thr
             } else if (object instanceof byte[] && JSON.isValid((byte[]) object)) {
                 byte[] strBytes = (byte[]) object;
                 contentLength = strBytes.length;
+                outputMessage.getBody().write(strBytes, 0, strBytes.length);
             } else {
                 contentLength = JSON.writeTo(
                         outputMessage.getBody(),