Cook chicken in a large skillet over medium-high heat until no longer pink and juices run clear, about 15 minutes.
Bring water, bouillon, and poultry seasoning to a boil in a large saucepan. Stir in rice, cover pan, and remove from heat. Let rice stand until water is absorbed, about 5 minutes.
Combine the cooked chicken, tomatoes, and mushrooms in saucepan with the cooked rice, and stir over medium-low heat until heated through. Serve hot.
