Gwen Renée Stefani Shelton (/stəˈfɑːni/ stə-FAH-nee; born October 3, 1969) is an American singer-songwriter and fashion designer. Stefani rose to fame as a member and lead vocalist of the band No Doubt, whose hit singles include "Just a Girl", "Spiderwebs", and "Don't Speak" from their studio album Tragic Kingdom (1995), as well as "Hey Baby" and "It's My Life" from later albums. During the band's hiatus, Stefani embarked on a solo pop career in 2004 by releasing her debut studio album Love. Angel. Music. Baby. Inspired by pop music from the 1980s, the album was a critical and commercial success. It spawned six singles, including "What You Waiting For?", "Rich Girl", "Hollaback Girl", and "Cool". "Hollaback Girl" reached number one on the Billboard Hot 100 chart while also becoming the first US download to sell one million copies.

Stefani's second studio album, The Sweet Escape (2006), yielded the singles "Wind It Up" and the title track, the latter of which was number three on the Billboard Hot 100 year-end chart of 2007. Her third solo album, This Is What the Truth Feels Like (2016), was her first solo album to reach number one on the Billboard 200 chart. Her fourth solo album and first full-length Christmas album, You Make It Feel Like Christmas, was released in 2017 and charted 19 tracks on Billboard's Holiday Digital Song Sales component chart in the United States. Stefani has released several singles with husband Blake Shelton, including "Nobody but You" (2020), which reached number 18 in the US. In 2024, she released her fifth studio album Bouquet.

Stefani's accolades include three Grammy Awards, an American Music Award, a Brit Award, a World Music Award, and two Billboard Music Awards. She received a star on the Hollywood Walk of Fame in 2023. In 2003, she debuted her clothing line L.A.M.B. and expanded her collection with the 2005 Harajuku Lovers line inspired by Japanese culture and fashion. Billboard magazine ranked Stefani the 54th most successful artist and 37th most successful Hot 100 artist of the 2000–2009 decade. VH1 ranked her 13th on their "100 Greatest Women in Music" list in 2012.

Gwen Renée Stefani was born on October 3, 1969, in Fullerton, California, and raised Catholic in nearby Anaheim. She was named after a stewardess in the 1968 novel Airport, and her middle name, Renée, comes from the Four Tops' 1967 version of the Left Banke's 1966 song "Walk Away Renée". Her father Dennis Stefani is Italian American and worked as a Yamaha marketing executive. Her mother Patti (née Flynn) is Irish-American and worked as an accountant before becoming a homemaker. Stefani's parents were fans of folk music and exposed her to music by artists like Bob Dylan and Emmylou Harris. Stefani has two younger siblings, Jill and Todd, and an older brother, Eric. Before leaving No Doubt to pursue an animation career on The Simpsons, Eric was the band's keyboardist.

She attended Loara High School, where she graduated in 1987. After high school, she attended Fullerton College and Cypress College. She then transferred to California State University, Fullerton, but dropped out to pursue her music career.

Her brother Eric introduced Gwen to 2 Tone music by Madness and the Selector. Eric and Gwen had originally started a band named Applecore. Then in 1986, he invited her to provide vocals for No Doubt, a ska band he was forming. She later became the sole lead singer when the other singer, John Spence, took his own life in December 1987. In 1991, the band was signed to Interscope Records. The band released its self-titled debut album in 1992, but its ska-pop sound was unsuccessful due to the popularity of grunge. Before the mainstream success of both No Doubt and Sublime, Stefani contributed guest vocals to "Saw Red" on Sublime's 1994 album Robbin' the Hood. Stefani rejected the aggressiveness of female grunge artists and cited Blondie singer Debbie Harry's combination of power and sex appeal as a major influence. No Doubt's third album, Tragic Kingdom (1995), which followed the self-released The Beacon Street Collection (1995), took more than three years to make. Five singles were released from Tragic Kingdom, including "Don't Speak", which led the Hot 100 Airplay year-end chart of 1997. Stefani left college for one semester to tour for Tragic Kingdom but did not return when touring lasted two and a half years. The album was nominated for a Grammy and sold more than 16 million copies worldwide by 2004. In late 2000, Rolling Stone magazine named her "the Queen of Confessional Pop".

During the time when No Doubt was receiving mainstream success, Stefani collaborated on the singles "You're the Boss" with the Brian Setzer Orchestra, "South Side" with Moby, and "Let Me Blow Ya Mind" with Eve. No Doubt released the less popular Return of Saturn in 2000, which expanded upon the new wave influences of Tragic Kingdom. Most of the lyrical content focused on Stefani's often rocky relationship with then-Bush frontman Gavin Rossdale and her insecurities, including indecision on settling down and having a child. The band's 2001 album, Rock Steady, explored more reggae and dancehall sounds, while maintaining the band's new wave influences. The album generated career-highest singles chart positions in the United States, and "Hey Baby" and "Underneath It All" received Grammy Awards. A greatest hits collection, The Singles 1992–2003, which includes a cover of Talk Talk's "It's My Life", was released in 2003. In 2002, Eve and Stefani won a Grammy Award for Best Rap/Sung Collaboration for "Let Me Blow Ya Mind".

Stefani's debut solo album, Love. Angel. Music. Baby., was released on November 12, 2004. The album features several collaborations with producers and other artists, including Tony Kanal, Tom Rothrock, Linda Perry, André 3000, Nellee Hooper, the Neptunes and New Order. Stefani created the album to modernize the music she had listened to in high school, and L.A.M.B. takes influence from a variety of music styles of the 1980s and early 1990s such as new wave, synthpop, and electro. Stefani's decision to use her solo career as an opportunity to delve further into pop music instead of trying "to convince the world of [her] talent, depth and artistic worth" was considered unusual. The album was described as "fun as hell but ... not exactly rife with subversive social commentary". The album debuted on the US Billboard 200 albums chart at number seven, selling 309,000 copies in its first week. L.A.M.B. reached multi-platinum status in the United States, the United Kingdom, Australia, and Canada.