Whisk brown sugar, gochujang, soy sauce, sesame oil, rice vinegar, garlic, ginger paste, and smoked paprika together in a bowl.
Add chicken pieces and stir to combine until evenly coated. Cover and refrigerate for at least 1 hour.
Preheat the air fryer to 400 degrees F (200 degrees C). Thread chicken pieces on skewers.
Place skewers in a single layer in the basket of the air fryer. Cook 6 minutes. Flip and cook 6 minutes more. An instant read thermometer inserted into the thickest part should read 165 degrees F (74 degrees C).
Transfer to serving plates and garnish with green onions and sesame seeds.