"So, here's my vow, starting from here and now, nothing comes between us," Little Mix sang, holding back tears as they shared a hug.
The lyrics are taken from the girl group's track, Between Us, which they performed on The Graham Norton Show.
The performance came as Little Mix, who has been together for 10 years, announced that they would be temporarily splitting.
"This was a special one," the band said about the performance, sharing a post on Instagram.
Perrie Edwards, Leigh-Anne Pinnock and Jade Thirlwall said on Friday that they would be "taking a break" after their 2022 tour but insisted it's not permanent.
The announcement comes a year after former member Jesy Nelson departed from the group.