Zest one lemon and juice both lemons. Mince the garlic cloves.
Add the lemon juice, lemon zest, olive oil, red wine vinegar, garlic, dried oregano, salt, and black pepper to a medium bowl.
If desired, add the Greek yogurt and crushed red pepper flakes for extra creaminess and a little heat.
Whisk everything together until the mixture is well combined and slightly emulsified.
Place 1½–2 pounds of chicken in a large resealable bag or covered container.
Pour the Greek Chicken Souvlaki Marinade over the chicken and turn or massage the chicken gently to coat it evenly.
Seal and refrigerate for at least 2 hours. For the best flavor, marinate for 4–6 hours.
Remove the chicken from the marinade and cook according to your preferred method, such as grilling the chicken on skewers until fully cooked.