Mingy Jongo appears first in Banjo-Tooie located in Cloud Cuckooland where there are two Mumbo Skulls being pink and one blue and appears in a random location. If there is a Minjo on the bottom floor then Mumbo is inside that skull or if it's a Jinjo instead, Banjo and Kazooie can see what appears to be Mumbo sleeping. He wakes up and tells them that he has a surprise, but when he gets up he attacks them, then his eyes turn red and he reveals himself to be Mingy Jongo, a cyborg disguised as Mumbo, who claims to be a bounty hunter.
He seals off the stairs and attempts to destroy Banjo with a series of fast-paced energy bolts from his zap stick, as well as the ability to teleport to various places in the room. Though every so often both abilities will short out and he attempts to recharge which is the duo's chance to strike. The more damage he takes, the more his robotic form, or, as he puts it, "cybotic-ness" is revealed, similar to the Terminator. Upon being defeated, he announces that his chances of beating Banjo are "minimal", his head pops off, his body spouting a strange green fluid, and he explodes.
He can also be fought by Mumbo if his skull is found before Mumbo's.
Mingy Jongo reappears as an item in Banjo-Pilot. When he is used, every other character becomes temporarily dizzy and moves slowly.
- Mingy and Targitzan are the only two characters to be fully defeated when defeated. Others can be talked to or escape.