Preheat the oven to 425°F (220°C).
In a large bowl, combine the olive oil, garlic powder, smoked paprika, dried thyme, dried oregano, salt, black pepper, and minced garlic. Mix well to create a marinade.
Add the chicken thighs to the bowl and toss to coat them evenly with the marinade.
Place the halved baby potatoes, baby carrots, and sliced bell peppers on a large sheet pan. Drizzle half of the remaining marinade over the vegetables and toss to coat.
Arrange the chicken thighs on top of the vegetables on the sheet pan.
Place lemon slices evenly over the chicken and vegetables.
Roast in the preheated oven for 35 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and the vegetables are tender.
Remove the sheet pan from the oven and let rest for 5 minutes.
Garnish with chopped fresh parsley before serving.