Knuckle Joe arrives in Dream Land as an antagonist seeking revenge against the Star Warrior he believes murdered his father. Delivered by Night Mare Enterprises in a ghostly form, he manifests his true physical appearance: purple skin, spiky white hair, green gloves, red shoes, and a green headband with a yellow jewel. This initial form differs from his later looks. He displays significant strength, easily overpowering Castle Dedede's Waddle Dees, clashing with Meta Knight, and hurling King Dedede's armored vehicle from the castle. Learning of Kirby from King Dedede, he searches Cappy Town and interrogates residents, revealing his vengeful motivation. He relentlessly attacks Kirby despite Kirby's lack of resistance. Meta Knight intervenes, halting the assault and revealing he himself is the Star Warrior responsible for the death of Joe's father. Meta Knight explains that Joe's father, a respected Star Warrior and his friend, was captured, corrupted by eNeMeE into a monster, and was reluctantly slain by Meta Knight to prevent further harm. He gives Joe his father's medallion, containing an infant Joe's image – a final gift showing his father retained goodness through love for his son. Joe initially rejects the truth, discards the medallion, and angrily denounces his father. Provoked by Meta Knight's challenge to prove he isn't consumed by monstrous rage, Joe battles Kirby again. During this rematch, Kirby inhales Joe's Smash Punch to gain the Fighter ability, leading to an even duel where Kirby mimics Joe's techniques. Overwhelmed by fury and determination to destroy Kirby, Joe transforms into a monstrous, spiked ball form with arms resembling Togeira. Kirby counters by inhaling a needle projectile to become Needle Kirby, defeats Joe, and reverts him to normal. This defeat and Meta Knight's plea for him to abandon anger lead to Joe's redemption. He accepts the truth about his father's fate, makes amends, and departs Dream Land expressing hope to fight alongside Kirby and Meta Knight in the future.

In subsequent appearances, Knuckle Joe adopts a blue jumpsuit, white gloves, blue shoes, a white headband with a red jewel, and tan skin, resembling his Helper design. He later returns posing as a Night Mare Enterprises Monster Manager, wearing a suit and tie. He releases small monsters to tire Kirby before deploying Masher, touted as Night Mare Enterprises' strongest monster. After Kirby exhausts himself inhaling the smaller monsters, Joe grants Kirby the Fighter ability to ensure a fair fight against Masher. He then reveals his true allegiance as a Monster Hunter targeting powerful monsters and teams up with Kirby to defeat Masher before leaving on good terms. During a battle against Masher 2.0 and other monsters, Joe is overwhelmed and injured. He escapes to Dream Land via monster transporter and is found unconscious by Sword Knight and Blade Knight. While recovering, he experiences a vision of his father guiding him. With Fighter Kirby's help and utilizing a hidden memory chip within his father's medallion, Joe destroys Masher 2.0. He makes his final appearance aiding Kirby directly in the assault on eNeMeE's fortress during the series' climax.

Throughout the anime, Knuckle Joe exhibits a headstrong, brutal, and vengeful personality, driven by a desire for challenging battles and initially consumed by vengeance. Despite this aggressive nature, he possesses a fundamentally good heart, ultimately channeling his fighting spirit against threats like eNeMeE and its monsters. His combat abilities include martial arts proficiency, energy projection from his fists and feet, powerful punches and kicks like the Vulcan Jab, Smash Punch, and Rising Break, and flight in his initial form. A notable behavioral quirk is his habitual gesture of wiping his nonexistent nose, which Kirby frequently imitates while in Fighter form or normally.