The Base: Place the sliced andouille sausage, onion, bell pepper, celery, and garlic into the slow cooker.
Season & Pour: Add the diced tomatoes (with their juices), chicken broth, Cajun seasoning, and dried thyme. Stir to combine the flavors.
The Rice: Stir in the uncooked long-grain rice. Push it down slightly to ensure most of the grains are submerged in the liquid for even cooking.
Slow Cook: Cover and cook on HIGH for 2.5 to 3 hours (or LOW for 5-6 hours). The rice should be tender and the liquid mostly absorbed.
The Shrimp Finish: About 15–20 minutes before serving, lift the lid and gently stir in the raw shrimp. Cover and continue to cook until the shrimp are pink, opaque, and curled.
The Final Toss: Gently fluff the rice with a fork, ensuring the sausage and shrimp are evenly distributed.
Serve: Garnish generously with freshly chopped parsley and green onions. Serve hot, perhaps with a side of cornbread to soak up the savory spices!