Preheat oven to 325°F (160°C).

In a saucepan, slowly heat mushroom soup, cream of celery soup, and milk together until well combined and warm.

Remove from heat and stir in the dry onion soup mix and raw rice.

Grease a 9 x 13 x 2-inch baking dish.

Pour the soup and rice mixture into the prepared baking dish.

Arrange the raw chicken pieces on top of the rice mixture.

Cover the dish tightly with aluminum foil.

Bake in the preheated oven for 2 1/2 hours, or until the chicken is cooked through and the rice is tender.