First, combine the diced onion, celery, bell pepper, and minced garlic in your slow cooker. Add the sliced sausage, chicken pieces, diced tomatoes with their juice, oregano, bay leaves, and Creole seasoning. Stir everything together until well-mixed.
Set your slow cooker to cook on high for 3 hours or on low for 4 to 5 hours. You'll know it's ready for the next step when the vegetables are completely tender. The chicken should be cooked through and easy to shred with a fork.
This long, slow cooking time allows the flavors of the "holy trinity," spices, and meats to meld together. This process creates a deeply savory and aromatic base for the final dish, which is the secret to a truly great jambalaya.
While the shrimp is an essential part of jambalaya, it's also delicate and can easily become rubbery if overcooked. To prepare it, use kitchen shears to cut along the back of each shrimp shell. This step makes them much easier to peel later while allowing the shells to add flavor to the broth.
Once the initial cooking time is complete, stir the prepared shrimp into the slow cooker. Cover the pot and continue cooking on the high setting for another 30 to 45 minutes. The jambalaya is done when the shrimp are pink, opaque, and cooked through.
The exact timing can vary depending on your slow cooker model, so keep an eye on it. The goal is to get the shrimp perfectly tender without letting them get tough.
While the shrimp is cooking, prepare the rice on the stovetop according to the package directions. Cooking the rice separately prevents it from becoming mushy in the slow cooker. Once cooked, keep it covered to stay warm.
After the shrimp is cooked, remove the bay leaves from the jambalaya. Give it a taste and season with additional salt and pepper if needed. You can either serve the jambalaya ladled over individual portions of rice or stir the cooked rice directly into the slow cooker for a more integrated dish.