Turn oven on to broil. Cook rice as directed on package.
Dice onion and bell pepper, and mince garlic. Set aside.
Heat oil in a large, deep, oven-safe skillet over medium heat. Add the onion, bell pepper, garlic, chili powder, cumin, salt, and pepper; stir and cook for 3-4 minutes.
Dice zucchini and drain tomatoes. Add to pan, along with corn. Cook for 3-4 minutes and then add cooked rice. Stir well to combine, then sprinkle with shredded cheese. Place in the oven until cheese is golden and bubbly.