Add the diced tomatoes, chicken broth, onion, celery, bell peppers, garlic, paprika, thyme, cayenne, salt, and black pepper to the slow cooker. Stir to combine.
Cover and cook on low for 5 hours until the vegetables soften.
Stir in the shrimp, then cover and cook on low for 30 more minutes until the shrimp turn pink and opaque.
While the shrimp finish cooking, prepare the brown rice according to package directions using 2 cups of water.
Spoon the rice into bowls, top with the shrimp creole mixture, and sprinkle with sliced green onions.