A gearbox brake trailer apparatus for safe downhill towing includes a frame having a front end, a left side, a right side, and a rear end. The front end has a trailer hookup configured to selectively engage a trailer hitch of a truck. A trailer deck is coupled to the frame. Each of a plurality of wheel pairs has an axle rotatably coupled between the left side and the right side of the frame and a pair of tires coupled to the axle. A gearbox is coupled to the frame and has a wiring harness configured to selectively engage with an electrical control plug of the truck. A drive linkage is coupled to the gearbox and is in operational communication with the gearbox and with the axle of a front most wheel pair of the plurality of wheel pairs to brake the rotation of the front most wheel pair.