In a bowl, mix olive oil, honey, thyme, garlic, balsamic vinegar, salt, and pepper until well combined.
Gently fold in the blueberries, taking care not to crush them.
Place chicken breasts in a bowl or resealable bag and coat evenly with the marinade. Refrigerate for at least 30 minutes.
Preheat oven to 400°F (200°C).
Heat an oven-safe skillet over medium-high heat with a small drizzle of olive oil. Sear chicken for 3–4 minutes per side until golden.
Pour the reserved blueberry marinade over the chicken.
Transfer skillet to the oven and bake for 15–20 minutes, until the internal temperature reaches 165°F (75°C).
Rest for 5 minutes before serving. Spoon blueberry thyme sauce over the chicken and enjoy this Best-Ever Blueberry Thyme Chicken at its peak flavor.