Preheat the air fryer to 375°F (190°C).
Rinse the corned beef under cold water and pat it dry with paper towels.
Rub the olive oil over the surface of the corned beef.
In a small bowl, mix together black pepper, garlic powder, onion powder, paprika, and dried thyme to create a spice rub.
Rub the spice mixture evenly over the corned beef, ensuring all sides are coated.
Wrap the corned beef in aluminum foil. Place the corned beef in the air fryer basket, fat side up.
Cook for 30 minutes at 375°F (190°C), then flip the corned beef and cook for an additional 30 minutes.
Check the internal temperature with a meat thermometer; it should reach 145°F (63°C) for medium doneness.
If necessary, cook for an additional 5-10 minutes until the desired doneness is reached.
Remove the corned beef from the air fryer, let it rest for a few minutes, then slice against the grain.