Combine the main ingredients in a large mixing bowl: shredded chicken, halved red grapes, diced red onion, and diced celery. Toss gently.

In a separate bowl, whisk together mayonnaise, lemon juice, salt, garlic powder, onion powder, and black pepper until smooth.

Pour the dressing over the chicken mixture and gently fold until well-coated.

Taste and adjust seasoning as needed, then serve immediately or refrigerate for 30 minutes before serving.

Store leftovers in an airtight container in the fridge for up to 3-5 days.