Formed on the 2012 edition of The X Factor UK), four-piece band Union J had originally started life as Triple J. After a successful audition, Triple J – consisting of members Josh Cuthbert, JJ Hamblett – reached the group battle but were beaten to the judges' houses round by GMD3. After fellow group Rough Copy had to leave the show due to visa issues, Triple J were brought in as a replacement with the addition of another contestant, George Shelley, to make the group a quartet. Renamed Union J, the four-piece went on to the semi-final, where they were eliminated.

Signing a deal with Sony subsidiary RCA Records at the end of 2012, the group released their debut single, “Carry You,” just six months later. In 2013, Union J released their self-titled, full-length debut album, featuring the single “Beautiful Life.” The album charted in the UK top ten. Union J then signed a new deal with Epic Records, but their second album “You Got It All – The Album” failed to have the same success, only peaking at number 28.

In March 2016, Shelley announced he was to leave the band to pursue other projects, and former Stereo Kicks member Casey Johnson was later announced as his replacement. Johnson left Union J after just a year in the band, and Union J revealed that they were to carry on as a trio. In July 2018, Union J released their brand new single “Alive”, their first single as a three piece band, and also the first single from their upcoming long awaited third album.

In October 2018, Josh Cuthbert released a statement revealing he had chosen to leave Union J, leaving the group as a duo. “Paralysed” was released in January 2019.

In January 2022, the original line-up comprising of Hamblett, Hensley, Cuthbert & Shelley confirmed they would be reforming to celebrate the band’s 10th anniversary. Following a one night residency at the London Palladium in May of that year, the band announced a nationwide tour.

In December 2022, the band surprise-released their third album, “Ten”, as part of their ten year anniversary celebrations.

The group issued a statement across their social media platforms announcing the cancellation of their reunion tour. Jaymi Hensley later announced his departure from the band the following month. Following Hensley’s exit, the band are believed to be on an indefinite hiatus.