In 1995, while singing backup and working on demos in Nashville, Chasez was drafted into *NSYNC by Timberlake and Chris Kirkpatrick, a performer based in Orlando who was interested in forming a singing group. With Joey Fatone and Lance Bass on board, the would-be supergroup headed to Europe, where they became stars rather quickly. The 1998 domestic release of the group's self-titled debut album launched a career stateside, and within two years J.C. Chasez would be a household name. When the first singles "I Want You Back", "God Must Have Spent a Little More Time on You" and "Tearing Up My Heart" hit the charts and began getting play on MTV's popularity-fueled daily series "TRL" at the end of the year, *NSYNC capitalized on its status with the well-received holiday album "Home for Christmas".

Excited to continue an upward trajectory, the group began working on a follow-up but were sidetracked by management issues culminating in a defection to Jive Records and a resulting $150 million lawsuit filed by boy band magnate and accused Svengali Lou Pearlman and parent company BMG Entertainment. As the case dragged on, the group's popularity waned, and when the matter settled in the last days of 1999, it became clear that a comeback for the five would be a tall order with a fan base comprised mostly of fickle teens.

*NSYNC more than rose to the occasion, going on a promotional tour that ensured that anyone who had a television or a radio was informed of the release date of the aptly titled "No Strings Attached". When the day came in March of 2000, both the media and the band themselves were shocked by sales figures. Within the very first day the record moved 1 million units, finishing up the week with a Backstreet Boys-busting 2.4 million count. Thanks to catchy singles like "Bye Bye Bye" and "It's Gonna Be Me" and the new wedding song staple "This I Promise You", *NSYNC was running up the charts and booming out of speakers all across the country. A highly entertaining and completely live HBO special "*NSYNC Live From Madison Square Garden" (2000) made believers out of some naysayers who felt the group was formulated and untalented, while appearances on everything from "Touched By an Angel" (CBS, 1999) to "The Simpsons" (Fox, 2001) made the members inescapable pop culture icons.

The group followed up with the successful "Celebrity", an album full of the quintet's own brand of self-described "dirty pop", a moniker relating to the edgy sound, not the relatively wholesome lyrics. One of the band's more prolific songwriters and an elemental factor in the shaping of their less syrupy, more experimental sound, Chasez sought to keep the group fresh and timely.

Making his big screen debut in the 2001 large format concert film "*NSYNC: Bigger than Live", Chasez didn't seem headed for the acting career that bandmates Timberlake, Fatone and Bass were pursuing despite his television background. He was featured along with the other *NSYNCers in the as yet unreleased romantic comedy "Jack of all Trades" (lensed 1999), produced by former manager Pearlman, and was set to star in a developing *NSYNC film.