Mike is an anthropomorphic white mouse. He wears a red suit and a white shirt under it with red pants and a red top hat, along with a dark purple tie. He has large white ears that are pink on the inside, and long whiskers. His tail is long and thin.
Mike may be small but he has a big and imposing character. Arrogant almost to a fault, Mike is not afraid to stand up to anyone bigger than him. However, he tends to bite off more than he can chew, and he is not an honest person, as he is caught cheating in a card game, swindling a trio of bears out of their money. This repeatedly came back to haunt him and affected those around him, even leading to the Moon Theater's destruction.
Despite his arrogance, Mike lives up to his skills as a singer and a musician, and his soulful crooning can move people to tears.
While not exactly a kind soul, Mike can appreciate others' kindness and merits, sincerely appreciating his girlfriend for saving him from the bears he'd cheated and cheering for Meena after repeatedly putting her down only to be awed by her amazing singing.
He has an ego, so confident in his talents that he assumed the prize money for Buster Moon's singing contest was guaranteed to be his that he bought a Lamborghini and spent all the money he'd swindled the bears out of, and refused to be upstaged that he came back to sing in the theater even when there was no money to be won.
Mike is a greedy, self-centered mouse with a Napoleon complex— and who happens to be a classically trained jazz musician with a voice like Sinatra. Driven by money, power, and the allure of beautiful female mice, Mike is constantly trying to be part of a crowd that doesn’t want him... unless, that is, he can somehow win Buster’s competition.
“A penny? How dare you! I happened to have studied in the Lincoln School of Music!”
–Mike, after a baboon gives him a penny for playing the saxophone
“All right, prove it, pal! Empty your pockets right now!”
–Mike, forcing the baboon to empty his pockets for extra money
“What do you smoke outta this?”
–Mike, after looking at the baboon's inhaler
“Aha! I knew it! You all saw it! You all saw it right here! The monkey lied! And next time, pick on someone your own size, ya bully.”
–Mike, after discovering a wad of cash from the baboon
“Well, look, I mean I'm sure you're gonna get a lot of namby-pamby animals in here saying things like, 'Oh, it's not winning, it's the taking part that counts!' Yeah, yeah, not me, pal. I'm here to win. That prize... it's mine!”
–Mike, taking part in an interview with Bob during the auditions
“Open it, will ya? I wanna see what a hundred thousand dollars look like!”
–Mike urging Buster Moon to open the chest so he can see the prize money
Mike is known as "The Crooner" according to the Sing Website.
Fan reactions of him were rather negative and caused the fans to accuse Illumination for ripping off Mr. Big from Disney's Zootopia. In actuality, Mike is more based on The Rat Pack, most notably Frank Sinatra.
His introduction scene is the last of five.
In his introduction scene, he claimed to have studied at the Lincoln School of Music.
Also in his introduction scene, he can be heard playing the late Dave Brubeck tune "Take Five".
In the closure of his introduction scene, he plays "Baker Street" for a brief moment.
He plays "Girl from Ipanema" by Tom Jobim, when he sees Nancy for the first time.
He was the first to question Buster Moon's prize money, as well as the first to discover the lack of money.