Main • Milli (voiced by Sophia Fox in the first season and Madeleine Rose Yen in the second, third and fourth seasons) is a 6-year-old girl. She has abilities related to patterns and measuring. By singing certain phrases, she can use patterns to solve problems. She is often the one to lead the team in many of their missions. In addition to being able to change the pattern of her dress, Milli can also alter the appearance of another object or person to match whatever pattern she is projecting on it, and her ponytails can extend to serve as measuring tools, such as a ruler, a weighing scale, and a
thermometer. Later seasons would make Milli extra proficient at martial arts, primarily when it comes to jumps and karate chops, in addition to obtaining her super harness. • Geo (voiced by Ethan Kempner in the first three seasons and Juan Mirt in the fourth season) is Milli's 8-year-old brother. His singing voice is provided by Brody Bett. He mainly solves problems based on shapes and can use them to make different kinds of objects, ranging from food, tools, and clothing to animals, vehicles, and buildings. For these purposes, he always has usage of his shape belt, which grants him the ability to summon any shape he needs. Later seasons would give him two more tools; the shape splitter, a
longsword that can cut a shape into any form needed, and the shape magnet, a
horseshoe magnet that can function as a grappling hook by attaching to any specific shape. He wears a pair of roller skates, and he rarely takes them off on dry land. • Bot (voiced by
Donovan Patton) is a green robot who can extend his limbs to reach things or use the screen on his belly (referred to as his "belly screen") to make calls and do math. He is Milli and Geo's primary caretaker, and as a robot features many retractable tools. • UmiCar (voiced by
P.T. Walkley) is the car that drives the team wherever their help is needed. He primarily communicates via engine noises that sound like a cat purring through an electronic filter, though he can pronounce his name with a clear and deep voice on rare occasions. He lacks a face in the first fifteen episodes of the first series and he gains a face in three episodes of the first series.
Recurring • DumpTruck is a living
dump truck who doesn't speak real words and doesn't play fair. • The Shape Bandit (voiced by P.T. Walkley) is a sneaky bandit cat who as his name implies, steals shapes. • Squiddy (voiced by
Chris Phillips) is a squid who creates all sorts of inventions. • The TroubleMakers (voiced by Nick Heatherington and
Jason Harris) are two mischievous foes who, with the use of their TroubleRays, stir up all sorts of trouble in Umi City and often sabotage Team Umizoomi in their tracks. • TroubleTruck is the duo's transportation unit. • DoorMouse (voiced in early episodes by Joe Narcisco and in later episodes by Chris Phillips) is a helpful friend who guards all the doors of Umi City. He also guards bridges, animals, and anything that needs guarding. Although he may sometimes get a little confused, he usually helps the Team on their missions and knows he can rely on help from them. • Shark Car is UmiCar's best friend. As his name implies, he is a toy car designed to look like a shark. ==Episodes==