Add brown sugar, smoked paprika, garlic powder, cayenne, black pepper, and salt to a bowl. Mix well using a fork to combine everything.
Place the pork loin on a flat plate. Using a kitchen towel, pat the pork loin dry.
Season the pork loin generously with the dry marinade mix. Make sure you season it from all sides.
Prepare the grill by cleaning it. Now, preheat it until it reaches 350 degrees F.
Place the pork loin on a hot grill for about 60 minutes. Make sure to flip it every 20 minutes to ensure it cooks on all sides.
Check the internal temperature of the pork loin with a meat thermometer. If it reaches 145 degrees F, remove the pork loin from the grill.
Place it on a plate and cover it with aluminum foil. Let it rest for 15 minutes.
Slice the pork loin and serve with your favorite side.
Enjoy!