Julian Fernando Casablancas was born in New York City on August 23, 1978, the son of American-Spanish businessman John Casablancas, the founder of Elite Model Management, and Jeanette Christiansen (née Chrisjansen), a Danish model and the 1965 Miss Denmark who later became an artist. When Casablancas was eight, his parents divorced. He once stated that he wanted to be closer to his father, which “translated into teenage rebelliousness”. His mother later married Ghanian painter Sam Adoquei, who helped shape Casablancas’ early musical taste by exposing him to music such as The Doors, which was markedly different from the mostly Phil Collins-influenced music he listened to as a child. He has several half-siblings, including an elder sister from his father’s first marriage, and three other siblings from his father’s third marriage.

Upon meeting future guitarist Nick Valensi and drummer Fab Moretti at Dwight School in Manhattan, the three began to play music together. He reconnected with guitarist Albert Hammond Jr. when the latter moved to New York. The band was formed in 1998 when Hammond was accepted into the band, with Casablancas as the lead vocalist and main songwriter and Nikolai Fraiture on bass.

The band began rehearsing a fourteen-song set which included “Alone, Together”, “Barely Legal”, “Last Nite”, “The Modern Age”, “New York City Cops”, “Soma”, “Someday”, “Take It or Leave It” and “This Life” (an early version of “Trying Your Luck”). Most of these songs now feature different lyrics. A demo sent to the newly reformed Rough Trade Records in the UK sparked interest there, leading to their first release via the website of the UK magazine, NME, who gave away a free mp3 download of “Last Nite” a week prior to the physical release as part of The Modern Age EP in 2001. The EP sparked a bidding war among record labels, the largest for a rock and roll band in years. Shortly after, The Strokes’ critically acclaimed debut album Is This It was released.

In 2005, Casablancas married Juliet Joslin, who was the assistant manager of The Strokes at the time. Their son, Cal, was born in January 2010. Their second son, Zephyr, was born on March 27, 2015. The couple divorced in 2019. Casablancas has maintained a sober lifestyle since 2009, stating that he was once “hungover for five years” during his drinking days. He is a lifelong fan of the New York Mets, although he claims the New York Jets’ selection of Sam Darnold over Josh Allen in the 2018 NFL Draft inspired him to “quit sports”.

Casablancas, along with the Strokes, provided vocals on a cover of Marvin Gaye’s “Mercy Mercy Me (The Ecology)” with Joshua Homme on drums and Eddie Vedder on backup vocals. The cover was released in 2006 as the B-side to “You Only Live Once”. Casablancas also provided bass guitar and backing vocals on Albert Hammond, Jr.’s “Scared” on his solo album Yours to Keep. He subsequently played a Casio guitar and provided backing vocals on “Sick, Sick, Sick” by Queens of the Stone Age.

In 2008, he recorded a song with Santigold (then known as Santogold) and Pharrell of N*E*R*D titled “My Drive Thru” for a Converse advertising campaign. During his solo phase, he recorded “Boombox” with Andy Samberg, Jorma Taccone, and Akiva Schaffer of The Lonely Island for their 2009 debut album Incredibad, and was featured in an SNL Digital Short for the same song. In addition, he also recorded “I Wish It Was Christmas Today”, a festive song based on a Saturday Night Live skit made popular by Jimmy Fallon, Horatio Sanz, Chris Kattan and Tracy Morgan. Casablancas performed the song live on Late Night with Jimmy Fallon on December 21, 2009, together with The Roots, Horatio Sanz and Jimmy Fallon. He also appeared in the 100th Digital Short, which aired on May 12, 2012.

Julian Casablancas made his live solo debut for a private party for fashion brand Opening Ceremony in Tokyo, Japan. To celebrate the release of the EP, Casablancas performed a series of shows in October 2009 at The Downtown Palace Theatre in Los Angeles with his live show band, The Sick Six. Members of The Sick Six include Jeff Kite (keyboard), Nelson London (synthesizer), JP Bowersock (guitar), Danielle Haim (percussion) and Alex Carapetis (drums). Casablancas then toured with The Sick Six in Europe, United States, Australia and Japan from November 2009 until July 2010.

In 2009, Casablancas founded Cult Records, the creative imprint for his solo album Phrazes for the Young. The label signed a partnership agreement with Kobalt Label Services in 2014, which includes representation and product management, physical distribution across multiple territories, digital distribution through AWAL, marketing and sync licensing services. Cult currently represents The Growlers, Har Mar Superstar, Songhoy Blues, Rey Pila, Karen O, Promiseland, The Strokes, The Voidz, Exhibition and Cerebral Ballzy. The label has also released works of Albert Hammond Jr., The Virgins, Reputante, INHEAVEN, Exclamation Pony and Nelson London (C O L O R).

Casablancas also collaborated with Danger Mouse and Sparklehorse on the song “Little Girl” on the 2010 album, Dark Night of the Soul, contributing the lyrics, lead and backing vocals, and guitar solo. Aside from vocal collaborations, he also contributed to the song “Forrest Gump” on Digitalism’s sophomore album I Love You, Dude in 2011. The electronica duo initiated a collaboration with Casablancas through his manager, and Casablancas contributed ‘a 30-second recording with him on guitar’ via email.

After the release of the two other albums and several major tours, the band took a five-year break, then returned with their fourth album Angles in 2011. The five-year hiatus was said to be the result of conflicting solo projects, sobriety issues, and unspoken emotions. The Strokes’ drummer Fab Moretti claimed the band struggled to process such “subconscious volcanic emotions,” partly because they were still “children” at the time.

Casablancas composed the original song “I Like the Night” as part of his endorsement deal to represent Azzaro’s new men’s fragrance Decibel, dB. The Azzaro Decibel television commercial featuring Julian aired in France on September 1, 2011.

Casablancas also lent his vocals to the title track, “Rave On”, on a 2011 tribute album to Buddy Holly, Rave On Buddy Holly. In 2016, Casablancas contributed three specially recorded The Velvet Underground and Lou Reed covers – Venus in Furs, Run Run Run and White Light/White Heat, under the title White Light White Heat (rock n roll animal live era version) – to the HBO television series, Vinyl. The songs were subsequently released on various soundtracks to the series by Atlantic Records.

The album release was followed by several headlining appearances at musical festivals, including Reading, Coachella, Lollapalooza and Austin City Limits. The band released Comedown Machine in 2013, as their last album under the contract with long-time label RCA, for which they did no promotion. The band released an EP, Future Present Past, on Casablancas’ own label Cult Records in 2016.

The Voidz, formerly known as Julian Casablancas + The Voidz, was formed in 2013. Along with Casablancas as lead vocalist, the band consists of Jeramy “Beardo” Gritter and Amir Yaghmai on guitar, Jacob “Jake” Bercovici on bass (as well as synthesizer), Alex Carapetis on drums and percussion, and Jeff Kite on keyboard. Wanting to earn a greater sense of respect as a band, rather than be perceived as a “side-project” of Julian’s, the band officially changed their name from “Julian Casablancas + The Voidz” to simply “The Voidz” during an ‘initiation’ video on the band’s YouTube page on December 8, 2017. Julian performed with Carapetis and Kite throughout the tour for his solo album, Phrazes for the Young. Through Carapetis, Casablancas met Gritter and Bercovici. Bercovici, having played music with Yaghmai for several of years, then connected him to Casablancas, forming what is now known as The Voidz.

Casablancas worked with Daft Punk on their 2013 album Random Access Memories by contributing lyrics, vocals, and a guitar solo to their song “Instant Crush”. The album won the 2013 Grammy Award for Album of the Year, with Casablancas as one of the co-recipients of the award.

In June 2014, Casablancas announced he would be releasing the debut album Tyranny. The album was released on his own label Cult Records and coincided with his move to Upstate New York. On September 23, 2014, the album was released, followed by a tour in the United States and United Kingdom. The album features the 11-minute single “Human Sadness”, a song whose demo was originally composed for the soundtrack of The Unseen Beauty, a short documentary film which profiled Casablancas’ stepfather, artist Sam Adoquei. The group revealed dates for a South American tour in August 2017.

In April 2015, it was revealed that Casablancas had worked on a song with Savages’ Jehnny Beth. The collaboration was later announced to be a cover of “Boy/Girl,” a 1983 duet by Danish punk band Sort Sol and Lydia Lunch. The music video, directed by Warren Fu, was released on December 4, 2015. The 7″ was released through both Cult Records and Pop Noire Records on December 18, 2015. Casablancas also wrote the song “Youth Without Love” for Har Mar Superstar’s 2016 album Best Summer Ever, and is featured on “No One There”, a song by Indian-born musician, Hammarsing Kharhmar (Exhibition).

In 2015, Julian also made an appearance on Leftöver Crack’s album, Constructs of the State. His vocals can be heard on the song Vicious Constructs. The song is sang by both Casablancas and Leftöver Crack lead singer Stza Crack(Scott Sturgeon).

Casablancas served as a co-producer on Rey Pila’s album released on Cult, The Future Sugar. In August 2016, Cult Records announced a new album with The Growlers, a Southern California-based band. It was also announced that Casablancas himself was producing the album, later known as City Club.

In 2016, he interviewed Henry Giroux, with whom he discussed whether or not the average American understands their existing struggles and unresolved conflicts. In September 2018, he appeared on Lee Camp’s show Redacted Tonight. The following month, Camp opened for The Voidz at a show in Houston, Texas. Casablancas endorsed Senator Bernie Sanders for the 2020 Democratic Party presidential primaries, and on the eve of the 2020 New Hampshire primary, The Strokes performed in support of Sanders at the University of New Hampshire. That October, a few days before the 2020 United States elections, Rolling Stone announced and released the first episode of Casablancas’s interview series, S.O.S. – Earth is a Mess. The show featured Democracy Now! host Amy Goodman and Andrew Yang as early guests, with Casablanca focusing much of his questioning on democratic reform and the influence special interest groups on politics and the media.

In December 2018, it was announced that the band would headline at Bilbao BBK Live in 2019, kicking off their global comeback. Numerous dates for festivals and shows have been announced afterwards, including a show at the Governors Ball Music Festival, marking the band’s return to New York City.

On March 30, 2018, The Voidz released their second album, titled Virtue. The album takes on a more political stance, dissecting universal concepts such as the paradox between what is perceived as “truth” and “lies”, when taking multiple perceptual view points into consideration. The album features track, “Pyramid of Bones”, which was featured on Adult Swim in April 2018, along with their single “Coul as a Ghoul” on the Adult Swim’s Singles Program.

Starting May 14, 2019, The Strokes teased some of new songs, starting with “The Adults are Talking,” live at The Wiltern in Los Angeles, giving remarks that there is possibilities for the Strokes to release a new album. On December 31, 2019, at Brooklyn NYE, they performed “Ode to the Mets” as an offer from Casablancas to sing live instead of singing songs from Angles as requested by fans. “I don’t remember Angles. What’s Angles?” Casablancas responded before suggesting that the band play the new song and later confirming the release of a new project.

In April 2020, The Strokes released the album The New Abnormal, which received positive reviews among critics, suggesting the band came back with a better maturity and cohesion among bandmates. The album project was started far back to 2016.

As of 2020, Casablancas lives in Los Angeles. In the early 2010s, Casablanca and his family moved to Upstate New York from Greenwich Village in Manhattan.