Preheat a large skillet to medium high heat and add oil. Season chicken, onions, and peppers with half of the fajita seasoning.
When skillet is hot, add the chicken, peppers, and onions. Cook 3-4 minutes per side, or until chicken is cooked through. Transfer chicken and vegetables to a plate and cover with foil to keep warm.
To the same skillet, add corn and black beans with the remaining fajita seasoning. Cook, stirring frequently, until warmed through.
