Preheat the oven to 375°F.
Pat the chicken thighs dry and season with salt and black pepper on both sides.
Heat the olive oil in a large Dutch oven over medium-high heat. Add the chicken thighs, skin side down, and sear for 4–5 minutes until golden. Flip and cook for 2–3 minutes more. Transfer the chicken to a clean plate.
Add the sliced onion and carrots to the Dutch oven. Sauté for 5–6 minutes until starting to soften.
Stir in the garlic and cook for 1 minute, just until fragrant.
Pour in the chicken broth, scraping up any browned bits from the bottom. Add salt and pepper to taste. Let it simmer for 1 minute.
Add the baby potatoes, rosemary, and thyme to the Dutch oven. Nestle the seared chicken thighs on top, then layer the lemon slices over the chicken.
Cover with the lid and transfer to the oven. Bake for 35–40 minutes, or until the chicken is fully cooked and the vegetables are tender (internal temp: 165°F).
Remove from the oven. Serve Lemon Chicken Thighs warm with the vegetables and pan juices spooned over top.