diff --git a/src/common/datetime/format_duration.ts b/src/common/datetime/format_duration.ts
index e823df03a3b0..e20f7e18af25 100644
--- a/src/common/datetime/format_duration.ts
+++ b/src/common/datetime/format_duration.ts
@@ -71,7 +71,7 @@ export const formatDurationDigital = (
   duration: HaDurationData
 ) => formatDigitalDurationMem(locale).format(duration);
 
-export const DURATION_UNITS = ["ms", "s", "min", "h", "d"] as const;
+export const DURATION_UNITS = ["s", "min", "h", "d"] as const;
 
 type DurationUnit = (typeof DURATION_UNITS)[number];
 
@@ -107,14 +107,6 @@ const formatDurationSecondMem = memoizeOne(
     })
 );
 
-const formatDurationMillisecondMem = memoizeOne(
-  (locale: FrontendLocaleData) =>
-    new Intl.DurationFormat(locale.language, {
-      style: "narrow",
-      millisecondsDisplay: "always",
-    })
-);
-
 export const formatDuration = (
   locale: FrontendLocaleData,
   duration: string,
@@ -163,13 +155,6 @@ export const formatDuration = (
       };
       return formatDurationSecondMem(locale).format(input);
     }
-    case "ms": {
-      const milliseconds = Math.floor(value);
-      const input: DurationInput = {
-        milliseconds,
-      };
-      return formatDurationMillisecondMem(locale).format(input);
-    }
     default:
       throw new Error("Invalid duration unit");
   }
diff --git a/test/common/datetime/format_duration.test.ts b/test/common/datetime/format_duration.test.ts
index 94ad9e116fc3..cd62785320e4 100644
--- a/test/common/datetime/format_duration.test.ts
+++ b/test/common/datetime/format_duration.test.ts
@@ -21,14 +21,6 @@ const LOCALE: FrontendLocaleData = {
 
 describe("formatDuration", () => {
   it("works", () => {
-    assert.strictEqual(formatDuration(LOCALE, "0", "ms"), "0ms");
-    assert.strictEqual(formatDuration(LOCALE, "1", "ms"), "1ms");
-    assert.strictEqual(formatDuration(LOCALE, "10", "ms"), "10ms");
-    assert.strictEqual(formatDuration(LOCALE, "100", "ms"), "100ms");
-    assert.strictEqual(formatDuration(LOCALE, "1000", "ms"), "1,000ms");
-    assert.strictEqual(formatDuration(LOCALE, "1001", "ms"), "1,001ms");
-    assert.strictEqual(formatDuration(LOCALE, "65000", "ms"), "65,000ms");
-
     assert.strictEqual(formatDuration(LOCALE, "0.5", "s"), "0s 500ms");
     assert.strictEqual(formatDuration(LOCALE, "1", "s"), "1s");
     assert.strictEqual(formatDuration(LOCALE, "1.1", "s"), "1s 100ms");