diff --git a/packages/eslint-plugin/src/rules/non-nullable-type-assertion-style.ts b/packages/eslint-plugin/src/rules/non-nullable-type-assertion-style.ts
index 8b7345e82401..4523715d1fbd 100644
--- a/packages/eslint-plugin/src/rules/non-nullable-type-assertion-style.ts
+++ b/packages/eslint-plugin/src/rules/non-nullable-type-assertion-style.ts
@@ -114,11 +114,21 @@ export default util.createRule({
         }
 
         if (sameTypeWithoutNullish(assertedTypes, originalTypes)) {
+          const expressionSourceCode = sourceCode.getText(node.expression);
+
+          const higherPrecedenceThanUnary =
+            util.getOperatorPrecedence(
+              services.esTreeNodeToTSNodeMap.get(node.expression).kind,
+              ts.SyntaxKind.Unknown,
+            ) > util.OperatorPrecedence.Unary;
+
           context.report({
             fix(fixer) {
               return fixer.replaceText(
                 node,
-                `${sourceCode.getText(node.expression)}!`,
+                higherPrecedenceThanUnary
+                  ? `${expressionSourceCode}!`
+                  : `(${expressionSourceCode})!`,
               );
             },
             messageId: 'preferNonNullAssertion',
diff --git a/packages/eslint-plugin/tests/rules/non-nullable-type-assertion-style.test.ts b/packages/eslint-plugin/tests/rules/non-nullable-type-assertion-style.test.ts
index 8b86634d2797..a5dd34cb94aa 100644
--- a/packages/eslint-plugin/tests/rules/non-nullable-type-assertion-style.test.ts
+++ b/packages/eslint-plugin/tests/rules/non-nullable-type-assertion-style.test.ts
@@ -199,6 +199,48 @@ declare const x: T;
 const y = x!;
       `,
     },
+    {
+      code: `
+declare function nullablePromise(): Promise<string | null>;
+
+async function fn(): Promise<string> {
+  return (await nullablePromise()) as string;
+}
+      `,
+      errors: [
+        {
+          column: 10,
+          line: 5,
+          messageId: 'preferNonNullAssertion',
+        },
+      ],
+      output: `
+declare function nullablePromise(): Promise<string | null>;
+
+async function fn(): Promise<string> {
+  return (await nullablePromise())!;
+}
+      `,
+    },
+    {
+      code: `
+declare const a: string | null;
+
+const b = (a || undefined) as string;
+      `,
+      errors: [
+        {
+          column: 11,
+          line: 4,
+          messageId: 'preferNonNullAssertion',
+        },
+      ],
+      output: `
+declare const a: string | null;
+
+const b = (a || undefined)!;
+      `,
+    },
   ],
 });