Gather all ingredients. Preheat the oven to 350 degrees F (175 degrees C).

Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Cook rotini in boiling water until tender yet firm to the bite, about 8 minutes. Drain.

Stir together cooked rotini, chicken, and mozzarella cheese in a large casserole dish.

Pour marinara sauce over pasta mixture; sprinkle with bread crumbs. Cover the dish with aluminum foil.

Bake in the preheated oven until cheese is melted, about 35 minutes.

Serve and enjoy.