In a medium bowl, whisk together the olive oil, lemon juice, Dijon mustard, honey, garlic, dried oregano, paprika, kosher salt, and black pepper until emulsified.
Place the chicken breasts in a resealable bag or shallow dish. Pour the marinade over the chicken, turn to coat evenly, and press out excess air if using a bag.
Refrigerate to marinate for 30 minutes to 4 hours (30–90 minutes for breasts to prevent over-acidifying; up to 4 hours for thicker pieces). Turn once halfway through for even coverage.
Remove the chicken from the marinade, letting excess drip off; discard the used marinade. For grilling, preheat to medium-high (400–450°F) and cook 5–7 minutes per side until the thickest part reads 165°F and juices run clear. For oven roasting, bake at 425°F on a rimmed sheet 16–22 minutes, flipping once, until 165°F.
Rest the chicken 5 minutes before slicing and serving.