Preheat the oven to 375°F. Grease a 9×13-inch baking dish and set aside.
Slice the bell peppers in half lengthwise. Remove the ribs and seeds.
Heat the olive oil in a large skillet set over medium heat. Add in the onion and cook for 3 to 4 minutes until softened.
Add in the chicken, white rice, black beans, corn, taco seasoning, and salsa. Stir to combine.
Fill each pepper with a heaping amount of the chicken mixture, making sure to pack the filling in. Place each stuffed pepper in the prepared baking dish. Top with shredded cheese.
Pour ½ cup of water into the bottom of the prepared baking dish. Then, cover with aluminum foil.
Bake for 25 minutes. Remove the foil and bake for another 5 minutes.
Top with chopped cilantro, if desired.