In a bowl, whisk together orange juice, lime juice, olive oil, soy sauce, garlic, cumin, oregano, chili powder, salt, and pepper.
Place chicken in a Ziplock bag or container, pour marinade over it, and seal. Refrigerate for 4+ hours (overnight for best flavor).
Preheat grill (or grill pan) to medium-high heat.
Remove chicken from marinade (shake off excess) and grill for 6–8 minutes per side (or until internal temp reaches 165°F/74°C).
Let chicken rest for 5 minutes before slicing. Serve in tacos, burrito bowls, or with rice and beans.