Keith plays a Machine Deck, augmented by powerful Magic and Trap Cards. Despite his reputation as a professional duelist, he cheats by hiding cards in his wristband. Similarly, when he wears the Rare Hunter robes, a claw mechanism feeds cards directly to his hand. Because the Duelists are so far from each other when Dueling at an arena, Keith's opponents rarely realize he is cheating.
As a professional Duelist, Keith has a large number of Decks which he keeps hidden inside of his jacket, consisting of several different Deck themes. During his time is Duelist Kingdom, he lends several cards to Bonz to fortify the young Duelist's Zombie Deck (including "Zanki" and "Crawling Dragon"), although Keith's Main Deck consists mostly of Dark Attribute Machine Type Monsters.
In his Duel with Yugi, Keith uses the cards from his Machine deck during the first half of the duel, but later switches to a style centered around the rare and powerful cards provided by the Rare Hunters, including the legendary "Zera the Mant".
In Project R.A., his Deck is based on Summoning high-powered cards, specifically "The Wicked Eraser", similarly to Yako Tenma's Deck. However, the main body of his Deck is composed of "Motor" cards. His cheating tactic, however, failed in his rematch against Jonouchi due to the black Duel Disk's cheat-prevention alarm.
Bandit Keith appears in his own part of Duelist Kingdom in Yu-Gi-Oh! Duel Monsters. His deck mainly consists of Zombie and Ghost cards, including all the Monsters used by Ghost Kotsuzuka under Keith's tutelage. Also part of the large pool of Keith's cards, many Warrior Monsters are also included. While the game predates Keith's Duel with Katsuya Jonouchi, a few Machine cards are included in his Deck; "Gatekeeper" and "Ground Attacker Bugroth" would later be used by Bandit Keith in the anime.