The group will release 'Proud' as this year's official Sport Relief song on March 19, with the profits to be donated to projects and charities that support underprivileged children.
The accompanying music video sees all four members perform the track in a low-lit and cold Wembley Stadium, while British Olympic medal winners Rebecca Adlington, Phillips Idowu and Louis Smith also feature.
Speaking about their involvement, JLS said: "We're so excited to be part of Sport Relief 2012 and to have the official single is a massive honour for us.
"Filming at Wembley Stadium was absolutely incredible and we're the first artist to film a music video there. When I was younger I dreamed about playing in a World Cup final at Wembley but this was just as good!
"Having been to Uganda to see some of the work that Sport Relief supports we're really proud to be part of a campaign that changes so many lives, so we hope the single raises a huge sum of money."
JLS will perform 'Proud' on the Sport Relief night of entertainment, which starts on Friday, March 23 at 7pm on BBC One.
They will also be performing a special one-off matinee concert for Sport Relief at The O2 on March 24 and will be joined by Olly Murs and Rizzle Kicks.
JLS are currently recording their fourth studio album and have indicated that their new material will include "'90s new jack swing/R&B-influenced music".
> JLS: 'We get better and better with each tour'
Watch the official music video for JLS's 'Proud' below: