Add the chicken and sausage to your slow cooker.
Toss in the onion, celery, broth, oregano, bay leaves, garlic, Cajun seasoning, salt, pepper, and cayenne.
Pour the diced tomatoes and their juices right over the top.
Give everything a gentle stir.
Cover and cook on low for 6–7 hours or high for 4–5 hours.
During the last 30 minutes of cook time, add in the thawed shrimp.
Serve warm over rice—and enjoy!