Heat oven to 425°F. Spray 10-inch skillet with cooking spray; heat over medium-high heat. Cook chicken in skillet about 5 minutes, turning once, until brown. Remove chicken from skillet.
In ungreased 13x9-inch pan, mix rice, contents of seasoning packet, squash, zucchini and bell pepper.
Add water to skillet; heat to boiling. Pour boiling water over rice mixture; stir to mix. Stir in cheese. Place chicken on rice mixture. Cover pan with foil.
Bake about 30 minutes or until liquid is absorbed and juice of chicken is no longer pink when centers of thickest pieces are cut.