In a large bowl, combine the chopped chicken, hard-boiled eggs, celery, and drained sweet pickle relish. Stir everything together until evenly mixed. The key is to chop everything finely so you get a little bit of each ingredient in every bite.

In a small bowl, whisk together the mayonnaise, sugar, salt, and black pepper until smooth and well combined. The sugar should dissolve completely into the mayo. Add the dressing to the chicken mixture and stir gently until everything is fully coated. You want every piece of chicken and egg covered in that creamy dressing.

Cover the bowl and refrigerate for at least 1 hour before serving. This chilling time allows all the flavors to meld together and creates that signature taste you remember from Chick-fil-A.