diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3015,6 +3015,10 @@
     if (Right.is(TT_CSharpNullConditionalLSquare))
       return false;
 
+    // No space between consecutive commas '[,,]'.
+    if (Left.is(tok::comma) && Right.is(tok::comma))
+      return false;
+
     // Possible space inside `?[ 0 ]`.
     if (Left.is(TT_CSharpNullConditionalLSquare))
       return Style.SpacesInSquareBrackets;
diff --git a/clang/unittests/Format/FormatTestCSharp.cpp b/clang/unittests/Format/FormatTestCSharp.cpp
--- a/clang/unittests/Format/FormatTestCSharp.cpp
+++ b/clang/unittests/Format/FormatTestCSharp.cpp
@@ -640,9 +640,12 @@
   verifyFormat(R"(private float[,] Values;)", Style);
   verifyFormat(R"(Result this[Index x] => Foo(x);)", Style);
 
+  verifyFormat(R"(char[,,] rawCharArray = MakeCharacterGrid();)", Style);
+
   Style.SpacesInSquareBrackets = true;
   verifyFormat(R"(private float[ , ] Values;)", Style);
   verifyFormat(R"(string dirPath = args?[ 0 ];)", Style);
+  verifyFormat(R"(char[ ,, ] rawCharArray = MakeCharacterGrid();)", Style);
 }
 
 TEST_F(FormatTestCSharp, CSharpNullableTypes) {