A convertible, all-terrain gear cart convertible between modes of manual propulsion, trailering, and support by a motor vehicle. A control arm with a trailer hitch connector permits trailering or manual propulsion and is pivotally coupled to a first end of a cargo bin, and a vehicle engaging member to permit support and transport by a motor vehicle projects from the second end of the cargo bin. Detachable, all-terrain wheels with lateral axes of rotation are retained at a mid-portion of the cargo bin. Cargo retention and roll bars are removably coupled to the cargo bin, and a retractable support leg can cooperate with the wheels to stabilize the gear cart. The vehicle engaging member can comprise a receiver with a mitered end forming a shelf that can be rested on a rigid tongue of a trailer hitch adapter to permit levering of the gear cart relative to a vehicle.