Heat olive oil in a heavy 5-quart Dutch oven over medium-high heat. Season chicken chunks lightly with Cajun seasoning and brown for 3-5 minutes until golden but not fully cooked. Remove chicken from pot and set aside.
In the same pot, add sliced sausage and brown for 5 minutes. Add the onion, bell pepper, and celery mix. Stir well, scraping the bottom to incorporate any browned bits. Cover and simmer on medium heat for 5 minutes, stirring once halfway through.
Return chicken to pot. Add tomatoes, broth, parsley, basil, garlic powder, Cajun seasoning, pepper, and salt. Mix thoroughly and adjust seasoning to taste.
Add raw rice and stir well to combine. Bring mixture to a boil, then cover and reduce heat to a very gentle simmer. Cook for 10 minutes, then carefully stir once to bring rice to the top. Cover again and continue cooking on lowest heat for 30 minutes or until rice is tender. Do not lift the lid during the final cooking period.
