The song peaked at number two on the Billboard Hot Dance Music/Club Play, and reached number one in the UK singles Chart in February 1999, where it dethroned The Offspring's "Pretty Fly (For a White Guy)" off the top spot. It scored Armand Van Helden his first chart-topper in the UK. "U Don't Know Me" peaked at number seven in France and Italy. The recording of this song went about in an unconventional way; the track was laid down, Van Helden went off and did his own thing, and left Harden to his own devices. This song was soon sampled by DJ duo Doman & Gooding for their hit single "Runnin'".
The strings featured in this song sampled the disco song "Dance With You", originally performed by Carrie Lucas. The drums are sampled from the 1992 classic house record "Plastic Dreams" by Jaydee. The full version of the track features an intro sampling dialogue from the Dial M for Monkey segment of the animated TV series Dexter's Laboratory. The specific episode was "Simion", whose voice actor (Maurice LaMarche) provided the spoken intro.