Preheat your oven to 425 degrees
Arrange all of the sliced peppers, onions and tomatoes on a sheet pan and season generously with fajita seasoning
Place thinly sliced chicken breast into a bowl and toss in fajita seasoning
Transfer the seasoned chicken on a sheet pan in a single layer
Place both sheet pans on rack set close to the center of a 425 degree oven and bake for 25-30 minutes
Once the chicken is cooked through and crispy and the vegetables are slightly charred, transfer the baking sheets onto a heat proof surface
Arrange the chicken and vegetables on a large platter or serve right off of the sheet pan
Build your fajitas and enjoy!