diff --git a/changelog_unreleased/css/13402.md b/changelog_unreleased/css/13402.md
new file mode 100644
index 000000000..c50ac315c
--- /dev/null
+++ b/changelog_unreleased/css/13402.md
@@ -0,0 +1,19 @@
+#### Keep trailing-comma for `var` function (#13402 by @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```css
+/* Input */
+.foo {
+  --bar: var(--baz,);
+}
+
+/* Prettier stable */
+.foo {
+  --bar: var(--baz);
+}
+
+/* Prettier main */
+.foo {
+  --bar: var(--baz,);
+}
+```
diff --git a/src/language-css/printer-postcss.js b/src/language-css/printer-postcss.js
index e3838f57d..2a54eb406 100644
--- a/src/language-css/printer-postcss.js
+++ b/src/language-css/printer-postcss.js
@@ -73,6 +73,7 @@ import {
   isAtWordPlaceholderNode,
   isConfigurationNode,
   isParenGroupNode,
+  isVarFunctionNode,
 } from "./utils/index.js";
 import { locStart, locEnd } from "./loc.js";
 import printUnit from "./utils/print-unit.js";
@@ -894,6 +895,7 @@ function genericPrint(path, options, print) {
       const isLastItemComment = lastItem && lastItem.type === "value-comment";
       const isKey = isKeyInValuePairNode(node, parentNode);
       const isConfiguration = isConfigurationNode(node, parentNode);
+      const isVarFunction = isVarFunctionNode(parentNode);
 
       const shouldBreak = isConfiguration || (isSCSSMapItem && !isKey);
       const shouldDedent = isConfiguration || isKey;
@@ -908,7 +910,17 @@ function genericPrint(path, options, print) {
               path.map((childPath, index) => {
                 const child = childPath.getValue();
                 const isLast = index === node.groups.length - 1;
-                const printed = [print(), isLast ? "" : ","];
+                const hasComma = () =>
+                  Boolean(
+                    child.source &&
+                      options.originalText
+                        .slice(locStart(child), locStart(node.close))
+                        .trimEnd()
+                        .endsWith(",")
+                  );
+                const shouldPrintComma =
+                  !isLast || (isVarFunction && hasComma());
+                const printed = [print(), shouldPrintComma ? "," : ""];
 
                 // Key/Value pair in open paren already indented
                 if (
diff --git a/src/language-css/utils/index.js b/src/language-css/utils/index.js
index 22a2ccc41..1a8763844 100644
--- a/src/language-css/utils/index.js
+++ b/src/language-css/utils/index.js
@@ -120,6 +120,10 @@ function isURLFunctionNode(node) {
   return node.type === "value-func" && node.value.toLowerCase() === "url";
 }
 
+function isVarFunctionNode(node) {
+  return node.type === "value-func" && node.value.toLowerCase() === "var";
+}
+
 function isLastNode(path, node) {
   const nodes = path.getParentNode()?.nodes;
   return nodes && nodes.indexOf(node) === nodes.length - 1;
@@ -444,4 +448,5 @@ export {
   isAtWordPlaceholderNode,
   isConfigurationNode,
   isParenGroupNode,
+  isVarFunctionNode,
 };
diff --git a/tests/format/css/trailing-comma/__snapshots__/jsfmt.spec.js.snap b/tests/format/css/trailing-comma/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 000000000..867f8c995
--- /dev/null
+++ b/tests/format/css/trailing-comma/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,27 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`var-func.css format 1`] = `
+====================================options=====================================
+parsers: ["css"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+.foo {
+	--bar: var(--baz,);
+  --bar: var(--baz     ,);
+  --bar: var(--baz     ,    );
+  --bar: var(--baz,);
+	--bar: var(   --baz1, --baz2    , );
+}
+
+=====================================output=====================================
+.foo {
+  --bar: var(--baz,);
+  --bar: var(--baz,);
+  --bar: var(--baz,);
+  --bar: var(--baz,);
+  --bar: var(--baz1, --baz2,);
+}
+
+================================================================================
+`;
diff --git a/tests/format/css/trailing-comma/jsfmt.spec.js b/tests/format/css/trailing-comma/jsfmt.spec.js
new file mode 100644
index 000000000..f232bbc6c
--- /dev/null
+++ b/tests/format/css/trailing-comma/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(import.meta, ["css"]);
diff --git a/tests/format/css/trailing-comma/var-func.css b/tests/format/css/trailing-comma/var-func.css
new file mode 100644
index 000000000..e3e6f6b51
--- /dev/null
+++ b/tests/format/css/trailing-comma/var-func.css
@@ -0,0 +1,7 @@
+.foo {
+	--bar: var(--baz,);
+  --bar: var(--baz     ,);
+  --bar: var(--baz     ,    );
+  --bar: var(--baz,);
+	--bar: var(   --baz1, --baz2    , );
+}