Heat a large skillet over medium-high heat. Cook and stir ground beef in the hot skillet until browned and crumbly, 5 to 7 minutes.
Combine water, rice, tomatoes, taco seasoning, salt, chili powder, and pepper in a rice cooker. Mix well. Seal rice cooker and select setting according to manufacturer's instructions. Cook until tender, about 30 minutes, stirring halfway through. Open the lid partway to release steam, and let rice sit, 5 to 10 minutes. Fluff rice with a fork.