Pat the chicken thighs dry and rub them with 1 tablespoon of the taco seasoning.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add the seasoned chicken and cook until cooked through and browned, about 5–7 minutes per side depending on thickness. Remove the chicken to a plate and cover with foil.
In the same skillet (leave any browned bits), add the rice, chicken broth, drained black beans, diced tomatoes with their juice, drained corn, and the remaining taco seasoning. Stir to combine.
Bring the mixture to a boil, then reduce heat to low, cover, and simmer 20–25 minutes until the rice is tender and the liquid is absorbed.
Return the cooked chicken to the skillet, cover, and heat until the chicken reaches 165°F (74°C) and is warmed through.
Sprinkle the shredded cheddar evenly over the skillet and heat until the cheese melts. Alternatively, place the skillet under the broiler for 1 minute to brown the cheese (watch closely).
Top with chopped cilantro, sliced olives, and sliced avocado. Serve warm.