In a mixing bowl, whisk together Dijon mustard, olive oil, orange juice, lemon juice, minced garlic, honey, salt, and black pepper until well combined.

Place the chicken breasts in a resealable plastic bag or shallow dish and pour the marinade over the chicken. Seal the bag or cover the dish and refrigerate for at least 30 minutes, or up to 2 hours for more flavor.

Preheat the grill to medium-high heat.

Remove the chicken from the marinade and discard the marinade. Grill the chicken for 6-7 minutes on each side, or until the internal temperature reaches 165°F (75°C).

Let the chicken rest for 5 minutes before slicing and serving.