"Woohoo" received mixed to positive reviews from
critics; most of them commended Aguilera's vocals and Minaj's appearance. However, others were not impressed with the song's sexual nature. Sara D. Anderson of
AOL Music said the "provocative, dancehall track nicely fuses Aguilera's powerful voice with Minaj's MC tactics". Benjamin Boles of
Now Magazine called the track the top track on
Bionic, commenting that Minaj's cameo "rescues" the song.
Alexis Petridis of
The Guardian said, "If you're going to do a five-minute song about cunnilingus, it's a good idea to enlist foul-mouthed rapper Nicki Minaj, whose bug-eyed contribution lends the proceedings an air of gripping abandon." Chris Ryan of
MTV Buzzworthy called the song "sexually explicit, funky club pop", saying "In Nicki Minaj, Aguilera has found the perfect partner for her erotic-pop adventures". He also called the song a "dirtier cousin of
Rihanna's '
Rude Boy' or '
Hollaback Girl'", and commended Minaj's verse.
Stephen Thomas Erlewine of
AllMusic said the track had an "incessant title loop piercing like a dental drill" and said it "doesn't work as temptation". He also commented "her crassness is no longer alienating as it was on
Stripped". Michael Cragg of
musicOMH also compared the song to dental work, commenting that the song, "which is about oral sex but is about as sexy as going to the dentist." Genevieve Koski of
The A.V. Club called the song "already-passé electro trash." In his retrospective commentary on the album
Bionic,
Billboard's Glenn Rowley called "Woohoo" a "raunchy banger", and Mike Wass of
Idolator shared a similar sentiment: "'Woohoo' is arguably the most iconic bop ever recorded about female genitalia". According to the
Gay Times writer Daniel Megarry, Nicki Minaj's verse in the song "happens to be" one of the very best efforts of her career.
Retrospective commentary Attitude opined that the song is "not subtle, but it is fun".
The Tab's Harrison Brocklehurst ranked "Woohoo" among Aguilera's greatest singles and labelled it as "bratty pop perfection". He further noted that the song is "a weird, hand-clappy masterpiece that’s aged marvellously". On a similar, top-40 list for the
Idolator "Woohoo" was ranked at number thirty-one; Mike Wass noted that the song "should have been a number one hit". ==Chart performance==