Rinse and dry pork tenderloin. Cut slits into top of pork tenderloin. Place minced garlic in the slits. Season pork with salt and pepper.
In a small bowl, whisk mustard, brown sugar, italian seasoning, and rosemary in a bowl until thoroughly combined. Pour and rub mustard mixture all over pork. Place in refrigerator to marinate for at least 2 hours.
Place pork tenderloin into greased air fryer basket. Cook on 400 degrees Fahrenheit for 18-20 minutes, until a quick read meat thermometer registers a temperature of 145 degrees Fahrenheit..
Remove from Air Fryer and allow to rest for 5 minutes before slicing. Enjoy :)