Chasez was born on August 8, 1976, in Bowie, Maryland. When he was five years old, his biological mother entrusted guardianship of her son to her own former foster parents Roy and Karen Chasez, who worked as an editor and a technology company consultant respectively. Chasez often danced at home in front of his foster parents despite being shy in public, eventually developing an interest in singing in order to become more confident. At the age of 13, he won in a national dancing competition, eventually being offered a position in The Mickey Mouse Club at the age of 15.

As a child, Chasez was extremely shy, but when a friend bet him $20 to enter a talent show, he won the contest and soon realized he had a knack for performing and that he really enjoyed singing. In 1989, his mother Karen Chasez noticed a small ad in the Washington Post announcing auditions for Disney’s The Mickey Mouse Club and encouraged Chasez to try out. He chose to audition, selecting the song “Right Here Waiting” by Richard Marx. Chasez was soon cast as a performer in the fourth season and stayed until the show’s cancellation in 1996. Since there was another Mouseketeer named Josh, Chasez went by his first and last initials, “JC”, to avoid confusion. It was during his time as a Mouseketeer that Chasez befriended future bandmate Justin Timberlake, along with other future entertainers including Christina Aguilera, Britney Spears, Tony Lucca, Keri Russell, and Ryan Gosling.

He wrote the song “Give In to Me” (a.k.a. “Give Me the Love I Need”) when he was 18 in 1994 and he sings the lead on it on Euge Groove’s debut CD.

JC Chasez and Justin Timberlake were the two lead singers of what would become the popular boy band NSYNC. The group was formed in 1995 and became popular in Europe in 1996. It was during this time that JC invented the art of Digital Sex, which he sang about on the track aptly titled, “Digital Get Down,” from the band’s sophomore album, “No Strings Attached.” In 1998, the band released its debut album *NSYNC which sold 11 million copies and became very popular in the United States. After the band had a series of legal struggles with manager Lou Pearlman, they signed with Jive Records. They released their second studio album No Strings Attached in 2000, which became the fastest-selling album of all time, selling 2.4 million copies in the first week. They held this record until 2015 when Adele surpassed the single-week sales record with her third album 25. Singles from the No Strings Attached album included “Bye Bye Bye”, “This I Promise You”, and the No. 1 hit “It’s Gonna Be Me”. The band produced their third studio album, Celebrity in 2001, which sold 1.8 million copies in the first week.

After the group’s Celebrity Tour in 2002, the band decided to take a hiatus. During this time, Chasez produced his own album, Schizophrenic. The band never formally disbanded, but since 2004, they have not reunited for any musical purposes, and there have been mixed reactions as far as whether the reunion would happen. In August 2013, JC rejoined with Timberlake and the rest of NSYNC for a one-time performance at the MTV Awards. In April 2019, Chasez reunited with bandmates Lance Bass, Joey Fatone, and Chris Kirkpatrick for a one-night performance as part of Ariana Grande’s headlining set at Coachella.

During NSYNC’s scheduled hiatus, Chasez pursued work as a songwriter and producer. His first solo single, “Blowin’ Me Up (With Her Love)”, co-produced by Dallas Austin, was released on the 2002 Drumline soundtrack.

In 2004, Chasez’s debut album Schizophrenic was released on Jive Records. Aside from Chasez, the album was produced by Dallas Austin, Basement Jaxx, Robb Boldt and Riprock ‘n’ Alex G.

In 2007, Chasez parted ways with Jive Records, indefinitely stalling the release of his second album, The Story of Kate. Two singles from the album, “Until Yesterday” and “You Ruined Me” have been released online. Timberlake, who helped produce a few songs for the album, said “In my opinion, he had the best voice out of all of us … Out of all the boy bands, call ’em what you will, he was the one that could out-sing all of us. And I’ve known him since I was 12, so it was fun to sit behind the board and push him.”

In November 2010, the song “If U C Kate” written by Dallas Austin, Taio Cruz, Alan Nglish, and Chasez was featured on the British band McFly’s album, Above the Noise. Chasez wrote and produced two songs on AJ McLean’s debut album Have It All, released in the US in February 2011.

In February 2012, Chasez announced via his website that he was holding auditions, together with the producer and songwriter Jimmy Harry, to form an all-girl group with ages between 18 and 24. Most of the band members were selected as of November 2012, and the group was named Girl Radical.

In 2014 Chasez was selected to join the North American tour of Andrew Lloyd Webber’s rock opera Jesus Christ Superstar as Pontius Pilate. Other cast members included Superstar winner Ben Forster and other well-known artists, including Incubus’ Brandon Boyd, Destiny’s Child’s Michelle Williams, and Public Image Ltd’s John Lydon. However, on May 30, 2014, the entire North American tour was abruptly canceled, with poor projected ticket sales cited as the reason.

Along with Miguel and Aloe Blacc, Chasez was featured on a new version of “My Girl” with Smokey Robinson on the album Smokey & Friends. In 2015, Chasez appeared, along with 3OH!3, on the title track of the Blues Traveler album Blow Up the Moon, and on the song’s accompanying music video. In 2016, Chasez starred in the film Opening Night, in which he played a dramatized version of himself.