In a large mixing bowl, combine the sugar-free mayonnaise, lemon juice, garlic powder, salt, and black pepper. Whisk until the dressing is smooth and well-emulsified.
Add the shredded or diced chicken breast to the bowl with the dressing.
Incorporate the diced celery, chopped pecans, sugar-free dried cranberries, and sliced green onions.
Fold the ingredients together using a spatula until every component is evenly coated with the dressing.
Taste the salad and adjust the salt or pepper to your preference.
Serve immediately or refrigerate in an airtight container for 30 minutes to allow the flavors to meld.