A firearm magazine safety lock for insuring that no ammunition is in the magazine or chamber that has a firearm magazine housing with a generally parallelepiped shape. The firearm magazine housing has two opposite ends, a bottom end and a chamber end. A lock is rotatably connected to the firearm magazine housing bottom end and is disposed within the firearm magazine housing. A slide block is drivingly connected to the lock. The slide block is rotatably connected to the firearm magazine housing chamber end. The slide block is for blocking a slide ejection port of the firearm from within a chamber of the firearm.