The JLS star was performing a special DJ set at the Capital FM Summertime Ball at Wembley Stadium on Sunday (9 June), when he ran into The Saturdays backstage.
Una Healy, Frankie Sandford, Vanessa White and Mollie King were among the star-studded lineup, but were without band mate Rochelle Humes, who is on maternity leave after giving birth to her and Marvin's first child, Alaia-Mai, on 20 May.
Marvin, however, was more than happy to step in for a group photo, joking on Twitter: "They're missing my baby @RochelleTheSats don't worry Roch I'm gonna fill in today!!!"
Rochelle, who was cheering on her hubby and band mates from home, replied: "Haha go u x."
The 24-year-old has been on maternity leave since March, but recently said how much she is looking forward to getting back on stage with her group later this year, including a performance at the Virgin Media V Festival in August.
> The Saturdays' Mollie King wows in LBD for night of partying
> JLS' Marvin Humes: 'I sing silly songs to Alaia-Mai'