In a medium bowl, toss the chicken cubes with chili powder, cumin, garlic powder, smoked paprika, salt, and pepper until evenly coated.
Heat olive oil in a large skillet over medium-high heat. Add chicken and cook for 8 to 10 minutes until the internal temperature reaches 165°F (74°C). Remove from skillet and set aside.
In the same skillet, add the corn kernels. Cook undisturbed for 3 to 4 minutes until charred, then stir and cook for another 2 minutes.
In a separate bowl, whisk together mayonnaise, sour cream, lime juice, and half of the cilantro.
Fold the charred corn into the mayonnaise mixture and stir in 1/4 cup of cotija cheese.
Divide the cooked rice into four bowls. Top each with a portion of the spiced chicken and the street corn mixture.
Garnish with the remaining cotija cheese, cilantro, and additional chili powder if desired.