diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts b/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts
index c73d8717c3e1..d29bd1292d02 100644
--- a/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts
+++ b/packages/eslint-plugin/src/rules/no-unnecessary-type-assertion.ts
@@ -13,6 +13,7 @@ import {
   getDeclaration,
   getModifiers,
   getParserServices,
+  getTypeName,
   isNullableType,
   isTypeFlagSet,
   nullThrows,
@@ -224,9 +225,13 @@ export default createRule<Options, MessageIds>({
         const uncastType = services.getTypeAtLocation(node.expression);
         const typeIsUnchanged = isTypeUnchanged(uncastType, castType);
 
-        const wouldSameTypeBeInferred = castType.isLiteral()
-          ? isImplicitlyNarrowedConstDeclaration(node)
-          : !isConstAssertion(node.typeAnnotation);
+        const isAssertionTypeUnionStringlike =
+          castType.isUnion() && getTypeName(checker, castType) === 'string';
+
+        const wouldSameTypeBeInferred =
+          castType.isLiteral() || isAssertionTypeUnionStringlike
+            ? isImplicitlyNarrowedConstDeclaration(node)
+            : !isConstAssertion(node.typeAnnotation);
 
         if (typeIsUnchanged && wouldSameTypeBeInferred) {
           context.report({
diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts
index db8309164efb..a4d34d1881bb 100644
--- a/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-unnecessary-type-assertion.test.ts
@@ -358,6 +358,16 @@ if (Math.random()) {
 x!;
       `,
     },
+    "let a = (Date.now() % 2 ? 'a' : 'b') as 'a' | 'b';",
+    `
+      const state: 'expired' | 'pending' = 'pending';
+
+      function main() {
+        return {
+          type: \`\${state}Request\` as \`\${typeof state}Request\`,
+        };
+      }
+    `,
   ],
 
   invalid: [
@@ -1151,5 +1161,16 @@ const a = '';
 const b: string | undefined = (a ? undefined : a);
       `,
     },
+    {
+      code: "const a = (Date.now() % 2 ? 'a' : 'b') as 'a' | 'b';",
+      errors: [
+        {
+          column: 11,
+          line: 1,
+          messageId: 'unnecessaryAssertion',
+        },
+      ],
+      output: `const a = (Date.now() % 2 ? 'a' : 'b');`,
+    },
   ],
 });