Preheat an air fryer to 320 degrees F (160 degrees C).
Whisk together olive oil, seafood seasoning, and cayenne pepper in a large bowl. Add peanuts and stir to coat. Transfer to the air fryer basket.
Cook in the preheated air fryer for 10 minutes. Toss and continue cooking for 10 minutes more.
Remove the basket from the air fryer. Season peanuts with salt, toss, and cook for 5 minutes more. Transfer peanuts to a paper towel-lined plate and let cool.