Heat olive oil in a skillet over medium heat and lightly brown the sliced sausage. This step adds extra flavor.
Add the browned sausage to the crockpot.
Place diced onion, bell peppers, celery, and garlic into the crockpot.
Stir in uncooked rice, diced tomatoes, tomato paste, and chicken broth.
Add Cajun seasoning, smoked paprika, thyme, oregano, cayenne pepper, salt, and black pepper.
Mix everything well to ensure the rice is evenly submerged.
Cover and cook on low for 4–5 hours or on high for 2–3 hours, until the rice is tender.
Add the shrimp during the last 20–30 minutes of cooking.
Stir gently, cover, and cook until the shrimp are pink and cooked through.
Taste and adjust seasoning before serving.