The current X Factor judge joined the former X Factor runners-up for a special duet at OJAM, the inaugural charity event held in aid of the JLS Foundation on Thursday night (6 June).
It's not the first time Gary has performed with Marvin Humes, Oritse Williams, Aston Merrygold and JB Gill. Earlier this year, the JLS boys joined Gary for a duet of 'Back For Good' which was included in his live concert DVD released in March.
Clearly, the group have become good friends, as last night Gary shared a photo of himself with JLS backstage alongside the caption: "Love these boys #gents."
Last night's charity evening held in Battersea, London raised £1 million for research into cancers that affect children, teenagers and young adults, which was a record amount raised in one evening for Cancer Research UK.
Despite JLS announcing they will split later this year, the band say they'll remain focused on their foundation going forward.
The JLS Foundation was founded in 2010 and supports causes close to the boys' hearts and causes that directly affect their fans.
Tweeting after yesterday's evening, new dad Marvin said: "What an incredible night and occasion.. £1million raised in 1 night for the JLS Foundation and @CR_UK #RecordBreaking thanks for the support."
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