diff --git a/ion/pom.xml b/ion/pom.xml
index 1c873c402..a7a9a6b14 100644
--- a/ion/pom.xml
+++ b/ion/pom.xml
@@ -38,7 +38,7 @@ tree model)
     <dependency>
       <groupId>com.amazon.ion</groupId>
       <artifactId>ion-java</artifactId>
-      <version>1.11.11</version>
+      <version>1.12.1</version>
     </dependency>
 
     <!-- Extends Jackson core, databind -->
diff --git a/release-notes/VERSION-2.x b/release-notes/VERSION-2.x
index 49b805f82..a0ebfb275 100644
--- a/release-notes/VERSION-2.x
+++ b/release-notes/VERSION-2.x
@@ -17,6 +17,9 @@ Active maintainers:
 2.23.0 (not yet released)
 
 #745: (avro) Fix Avro bugs
+#800: (ion) Upgrade `ion-java` dependency to 1.12.1 (from 1.11.11, which has
+  binary-write corruption bug)
+ (fix by @cowtowncoder, w/ Claude code)
 
 2.22.3 (not yet released)