Twin brothers Matt and Luke Goss - who enjoyed a huge hit with the track When Will I Be Famous? - will play London's O2 Arena on 19 August next year.
The pair, who are now 48, inspired teenagers to wear bottle caps on the shoes in their heyday.
Matt, who has enjoyed a solo career since they split, said: "As the lead singer of the band, my musical connection has always been with Luke. Bros is Matt and Luke."
Bros last played together in 1989 and split in 1992.
Matt recently dismissed speculation about a reunion, saying: "Bros is always surrounded by rumours. I think if it was going to happen it would come out of my mouth and my brother's mouth."
The band will perform their old hits. Luke said he is excited about the reunion, and a little nervous.
"I'm like a big kid right now. I'm pinching myself," he said.
He said he always wanted to reunite with his brother and "didn't want to resist it any more. I have always wanted it to happen in my heart but wanted it to be at the right time," he said.
"This is a dream come true. It's always something I've wanted to do but at the right level."
Matt promised the concert would be a "spectacle" and the best show Bros have ever performed.
He said he and his brother "were in a good place together."
Matt said Craig Logan - who left the band in 1989 - was welcome to join them, but he was focused on his career as a music executive. Asked whether there would be more gigs, Luke said the duo would "see how it goes".