Cook the whole wheat penne pasta according to package instructions until al dente. Drain and rinse under cold water to cool.
In a large bowl, combine the cooked pasta, diced chicken, cherry tomatoes, cucumber, red onion, and chopped basil.
In a small bowl, whisk together the olive oil, lemon juice, garlic powder, salt, and pepper.
Pour the dressing over the pasta salad and toss gently to combine all ingredients evenly.
Sprinkle the crumbled feta cheese on top and give it a light toss.
Chill the pasta salad in the refrigerator for at least 30 minutes before serving to allow the flavors to meld.