In a large mixing bowl, whisk together the lime juice, lime zest, chopped cilantro, olive oil, minced garlic, chili powder, cumin, kosher salt, and black pepper until combined.
Add the chicken thighs to the bowl and toss thoroughly to coat each piece in the marinade.
Cover the bowl with plastic wrap or a lid and refrigerate for at least 30 minutes or up to overnight to marinate.
Preheat a grill or heavy-duty grill pan to medium-high heat and lightly oil the grates or pan.
Place the marinated chicken thighs on the hot grill and cook 5–7 minutes per side, until the internal temperature reaches 165°F (74°C) and juices run clear.
Remove the chicken from the heat and cover loosely; let rest at least 5 minutes before slicing and serving.