Place the chicken breasts in the bottom of the slow cooker. Add the uncooked rice on top.
In a bowl, stir together the cream of chicken soup, chicken broth, garlic powder, salt, and pepper until smooth. Pour this mixture over the rice and chicken.
Cover and cook on low for 5 hours.
Remove the chicken breasts, shred or chop them, and return the pieces to the slow cooker. Stir in the broccoli florets.
Sprinkle the shredded cheddar cheese over the top. Cover and cook for 30 more minutes until the broccoli is tender and the cheese has melted. Stir gently before serving.