In a mixing bowl, combine the vegetable oil, lemon juice, minced garlic, rosemary, paprika, salt, and pepper.
Add the chicken cubes to the marinade and make sure they are well coated. Cover the bowl and refrigerate for 30 minutes or up to 2 hours for maximum flavor.
While the chicken is marinating, prepare the onion. Thread the marinated chicken pieces onto the soaked wooden skewers, alternating with the onion chunks. Leave a small space between each piece to ensure even cooking.
Preheat your air fryer to 375°F (190°C) for about 5 minutes. Place the chicken skewers in the preheated air fryer basket. You may need to cook them in batches, depending on the size of your air fryer.
Cook for 10-12 minutes, turning the skewers halfway through the cooking time, until the chicken is cooked through and has reached an internal temperature of 165°F (74°C). The vegetables should also be tender and slightly charred.
Carefully remove the chicken skewers from the air fryer and let them rest for a few minutes. Serve hot with your favorite dipping sauce or a side salad!