A reviewer from
Cashbox described the song as "naughty and suggestive yet not particularly explicit
R&B/pop". Arion Berger from
Entertainment Weekly complimented it as "irresistible". Dennis Hunt from
Los Angeles Times found that all it "has going for it is sexy lyrics."
James Hamilton from
Music Week's
RM Dance Update called it a "sweetly cooing young guys crooned gorgeous sineous sexy swayer" in his weekly dance column.
Stephen Holden from
New York Times wrote, "'I Wanna Sex You Up' has a loping pop
Latin beat that is similar to
the Young Rascals' '
Groovin'' and
Laura Nyro's '
Stoned Soul Picnic', and a piercing lead vocal by
Bryan Abrams, whose voice resembles that of the late-1960's
Stevie Wonder."
David Fricke from
Rolling Stone declared it as "a crafty blend of
doo-wop doo-wah and
hip-hop clatter so irresistible it makes you willing to forgive the utter banality of the lyrics."
Retrospective response Alex Henderson from
AllMusic named the song as one of the "moments" on the
C.M.B. album, describing it as a slow jam which samples rapper
Slick Rick "in a rather clever fashion". "I Wanna Sex You Up" was ranked number 40 on
Blender's list of the "50 Worst Songs Ever" and
VH1's "100 Greatest Songs of the '90s". In a 2017 retrospective review, Pop Rescue commented, "This song stood out from the rest of the charts when it was released in the UK, and that along with the boys’ breathy sexy promises and the inclusion of ‘sex’ in the song title made this track a sure-fire hit. Musically it's quite a simple song, allowing the vocals to really shine here – and to their credit, their vocals worth together really well." ==Chart performance==