Dice celery, bell pepper, onion, and chicken. Place in Multipurpose Steamer.
Stir in water, diced tomatoes, rice, and seasoning. Make sure the rice is submerged under the liquid. Microwave, uncovered, on high for 16–18 min, stirring halfway, or until rice is tender.
Add shrimp to Multipurpose Steamer; stir to combine. Microwave on high, uncovered for 2 min, or until shrimp are warmed through. If you have time, let the jambalaya rest a few minutes to allow the moisture to redistribute in the rice.