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 browned and cooked through, about 5–7 minutes per side depending on thickness. Transfer to a plate and tent with foil.
In the same skillet (leave any browned bits), add the rice, chicken broth, black beans (drained), 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 for 20–25 minutes until the rice is tender and 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 shredded cheddar evenly over the skillet and heat until the cheese melts; alternatively broil briefly in the oven for 1 minute to brown the cheese, if desired.
Top with chopped cilantro, sliced olives, and avocado slices, then serve hot.
