Preheat a skillet over medium heat and add olive oil.
Season the chicken with salt, pepper, and garlic powder. Add to the skillet and cook until browned and cooked through, about 5-7 minutes per side. Remove from skillet and set aside.
In the same skillet, add the sliced bell pepper and onion. Sauté until they are soft and slightly caramelized, about 6-8 minutes.
Return the chicken to the skillet with the vegetables. Stir to combine and heat through.
Lay slices of provolone cheese over the chicken and vegetable mixture, allowing it to melt.
Slice the hoagie rolls open and fill them with the chicken, peppers, onions, and melted cheese.
Serve the chicken Philly cheesesteak sandwiches hot.