A Jumbo Cannon, fittingly, is shaped like a small cannon. Its body is dark grey with yellow highlights and red rivets. It has four short, sharp, black legs, a large, black spike on either of its sides, and a grey base. The Heartless's face is a black sphere with glowing yellow eyes set at an angle in the front of the cannon's body. The actual barrel of the cannon is light grey and has several black designs that cause it to resemble a face, with the mouth of the cannon being the nose. It also sports a short, curled, yellow fuse in its back.
The Jumbo Cannon's name refers to its size when compared to similar Heartless, as well as the weapon it is based on. Its Japanese name, "Huge Cannon", has a similar meaning.
The Jumbo Cannon cannot be hurt by Fire, but Thunder and Blizzard inflict some damage. Aero would be a good spell to bring along when one ventures to Olympus Coliseum, as it does the most damage. It can occasionally be frozen, but it moves around often, thus it is hard to freeze.
The Jumbo Cannon's only attack is to lock onto you (which you will see a Heartless Emblem under you), and it will fire at you. This attack can leave you Ignited. The attack may be hard to avoid, but can be dodged by gliding or air sliding.