In a large bowl, combine the cooked chicken, corn, black beans, cherry tomatoes, cucumber, red bell pepper, red onion, and avocado.
In a separate small bowl, whisk together the lime juice, olive oil, chili powder, cumin, salt, and pepper until well combined.
Pour the dressing over the salad mixture and toss gently to coat all the ingredients evenly.
Serve the salad over a bed of mixed greens. Garnish with chopped cilantro.
For best flavor, let the salad sit for about 10 minutes before serving to allow the flavors to meld.