Weiland was born Scott Kent but his name was changed when his stepfather, David Weiland, adopted him. Though born in Santa Cruz, he moved to Chagrin Falls, Ohio by age 5, and lived there until he was 15, at which point he returned to San Diego, California.

Weiland met bassist Robert DeLeo at a Black Flag concert, and shortly thereafter formed the band Mighty Joe Young with DeLeo's brother Dean on guitar and Eric Kretz on drums. The band's name was changed to Stone Temple Pilots when it was discovered shortly after signing with Atlantic Records that "Mighty Joe Young" was already taken. The name "Stone Temple Pilots" itself has no significance other than forming the acronym "STP" which Weiland remembered having a sticker of on his bike as a child.

Weiland composed the band's lyrics and sang lead vocals. In 1992, they released their first album, Core, and their first hit, "Sex Type Thing" led to them becoming one of the most commercially successful bands of the grunge movement, the music genre that was spawned out of Seattle in the late eighties and became rock's central movement of the early-mid 1990s. The band was widely accused of copying bands like Pearl Jam and Alice in Chains in an attempt to cash in on the scene's burgeoning popularity. The band itself has rejected such comparisons and cited The Doors and ragtime guitar as more influential on their sound.

In 1994, Weiland married Janina Castaneda and STP released their second album, Purple, which saw the development of a more unique identity for a band. The year prior, STP toured with the Butthole Surfers, where it is widely believed Weiland picked up his heroin addiction, a habit that would checker most of the rest of his career.

In 1995, Weiland was caught and convicted of buying rock cocaine. He was sentenced to one year's probation. Issues with drug use did not clear up after his sentence, and STP was forced to cancel most of their 1996-1997 tour in support of their third release, Tiny Music... Songs from the Vatican Gift Shop.

With Weiland's status in the band uncertain and unpredictable, STP went on hiatus. Robert, Dean and Eric created the group Talk Show with lead singer Dave Coutts, and Weiland released a solo album in 1998 called 12 Bar Blues. Weiland composed as well wrote the lyrics for most songs on the album, and collaborated with several artists, notably Daniel Lanois, Sheryl Crow and Jeff Nolan. The album was not a commercial hit, and Weiland was eventually caught in Manhattan buying heroin, ending his brief tour. A previous conviction in Los Angeles, coupled with numerous probation violations, got Weiland sentenced to jail time.

The constant relapses were too much for his marriage, and Castaneda filed for divorce. His period in jail had apparently helped to wean him from his habit, and once released, he rejoined the Stone Temple Pilots, and married again, to model Mary Forsberg, with whom he has two children, Noah and Lucy.

In late 2001, Weiland's battles with the law continued. He was arrested on domestic violence charges in Las Vegas, apparently for shoving Forsberg. While the charges were eventually deferred upon the couple agreeing to counselling, Forsberg eventually filed for divorce but the couple finally reconciled. Weiland's career also took a hit, with an altercation between Weiland and guitarist Dean DeLeo on the final gig of STP's Shangri-La Dee Da tour leading to the band's demise.

Weiland was eventually asked to join a band started by former Guns N' Roses members Slash, Duff McKagan, and Matt Sorum, along with guitarist Dave Kushner, with the working title "The Project", and later becoming "Velvet Revolver".

Velvet Revolver's debut album "Contraband" was released in the spring of 2004. It debuted at Number One on the Billboard 200 and has sold over three million copies world-wide to date.

Weiland was most recently arrested on October 27, 2003, in Hollywood, California, after a traffic collision. He was charged with driving under the influence of drugs and alcohol. In July of 2005, his drug charges were dismissed after he successfully completed rehab and subsequent drug tests.

In March 2006, Weiland joined covers band Camp Freddy.