The group will be performing at the event for the second year running and this time will get the honour of kicking off the evening.
JLS announced the news on Capital FM's Breakfast Show this morning (May 11th).
"We are opening the Capital Summertime Ball this year," said singer Oritse Williams.
"We're the first performers onstage, I don't want to brag, but you know."
It follows comments by bandmate Marvin Humes, who said recently that the event is particularly important for the group.
"The Summertime Ball is always special to us because it was the first place we ever performed in front of anybody when we performed Beat Again and Umbrella we had just to come out of the show (X-Factor)," he said.
The Capital FM Summertime Ball takes place at London's Wembley Stadium on June 12th. Tickets are available at Premier Events website.
