Preheat your oven to 425°F (220°C).
In a large bowl, combine the ranch seasoning mix, garlic powder, onion powder, paprika, salt, and black pepper.
Add the olive oil to the spice mixture and stir until well combined.
Pat the chicken thighs dry with paper towels and place them in the bowl with the seasoning mixture. Toss to coat the chicken evenly.
Arrange the seasoned chicken thighs skin-side up on a baking sheet lined with parchment paper.
Bake in the preheated oven for 35-40 minutes, or until the chicken is cooked through and the skin is crispy. The internal temperature should reach 165°F (74°C).
Remove from the oven and let the chicken rest for 5 minutes before serving. Garnish with fresh parsley.