The All Terrain Armored Transport was an imposing, quadrupedal combat walker that stood 22.5 meters tall. Due to their impressive appearance, it was used as much for psychological effect as for tactical reasons. Additionally, it also served as transports for combat personnel. The vehicle's cockpit and sensor array was located in the "head" part,^[4] which also carried the main armaments: dual medium blasters located on the "temples," and a pair of heavier laser cannons fitted on the "chin." Inside the cockpit stood an AT-AT commander behind two AT-AT pilots who controlled the walker's movement.^[8] The armor plating of the AT-AT was impervious to blaster bolts, however the neck and joints proved weak spots and could be damaged by blaster cannons and other heavy weaponry. The entire walker was vulnerable to other AT-AT fire, if one happened to be hijacked and turned against the other.^[2][5][9]

Connecting the "head" to the "body" was what was dubbed the "tunnel," which would lead to a troop compartment capable of ferrying numerous soldiers, along with a vehicle bay at the walker's rear that held five 74-Z speeder bikes. The main, rectangular troop hatch was located in the middle of the walker's side, while two smaller escape hatches were located both to the main hatch's immediate left and right. The walker's tail end consisted of filtered atmosphere intakes on its upper part, while a blaster cannon energizer was located within. At the bottom of the behemoth was the walker's fuel slug tank, which had a reputation of being dangerous. The walker's four legs were aided with the assistance of ankle drive motors, while inside the giant footpads were several terrain scanners.^[4]

There was a more heavily-armored variant with a darker color scheme called an Elite AT-AT.^[10