diff --git a/docs/source/format/CanonicalExtensions.rst b/docs/source/format/CanonicalExtensions.rst
index 1693179ecf298..a72d8cb3c8224 100644
--- a/docs/source/format/CanonicalExtensions.rst
+++ b/docs/source/format/CanonicalExtensions.rst
@@ -259,7 +259,8 @@ JSON
 * Extension name: `arrow.json`.
 
 * The storage type of this extension is ``StringArray`` or
-  ``StringViewArray``.
+  or ``LargeStringArray`` or ``StringViewArray``.
+  Only UTF-8 encoded JSON is supported.
 
 * Extension type parameters: