Raised in Philadelphia, he attended Leighton Park School in ReadingUK (for a year in 1988–89 before being expelled) known for its strength in music. Zender left his home when he was seventeen with two thousand pounds that his mother had saved, to give him a head start in life.
As Zender said, he never had good business acumen, so instead of investing that money in some way, he went a music store and bought a Warwick Streamer bass guitar which cost nearly the whole amount given to him by his mother. Before picking up a Warwick, Zender played a Music Man Stingray bass guitar. Of his early bands, the most famous was the prank rock group Fabulous, a 1991 outfit chiefly made up of NME writers and photographers. He also said that in another interview, he played a drum with a circus group without animals at that time.
Zender was one of the members of the funk/acid jazz band Jamiroquai. The band has been in existence since 1992. He joined the band when the album released in 1993. To be auditioned for Jamiroquai, Stuart met leader Jason Kay(Jay Kay) through Nick Van Gelder(the first drummer in Jamiroquai), acquaintance of the circus group. While enrolled in Jamiroquai, he became famous by playing their impressive melodic basslines written by Jay Kay. Zender was asked to become an official Warwick basses endorser. He received a number of unique custom shop Streamer models.
Zender left Jamiroquai in 1998 during the recording of their fourth album, Synkronized, because of conflicts with the band leader Jay Kay. The circumstances behind his departure have never been fully revealed, but Zender told of his anger that he and the other band members were not being credited enough for assisting in songwriting and producing, despite the fact that they earned more rewards and credits than most musicians hired by other bands. He also said that he resigned to spend more time with his new wife Melanie Blatt, one of UK girl group All Saints, and their new baby Lilyella.
After Jamiroquai, Zender had his own project with the British soul artist, Don-E, called "AZUR" which signed a record deal with d'Angelo's label. However, the project was shelved and was then available on the Internet for a short time. He has also played bass guitar with other artists, including All Saints, Omar, Lauryn Hill, D'Angelo, Gorillaz, Samuel Purdey, Ms. Dynamite and Stevie Wonder. He and Melanie Blatt were together for seven years. They have one daughter, named Lilyella. Some of Zender's most recent work should have been with his latest band "LEROI". Zender explained they were signed to Geffen Records in Los Angeles but The deal fell through after the heads of the company, Polly Anthony and Jordan Shurr, who signed them, were made redundant.