The singing group said Gately died Saturday while vacationing with his partner, Andy Cowles, on the island of Majorca, the BBC reported Sunday.
Boyzone lead singer Ronan Keating said he was devastated by the news of Gately's death. The group also released a statement expressing members' sadness.
"Ronan, Keith, Mikey and Shane are devastated by the news and send their deepest sympathies to Stephen's family and his many friends all over the world," the statement said.
Singer Elton John also offered condolences on behalf of himself and his partner, David Furnish, the BBC reported.
"David and I are stunned by this tragedy. Stephen was the kindest, gentlest soul," John said.
"We send our love and condolences to his partner Andy and to all his friends everywhere."
CNN said Boyzone, formed in the early 1990s, reunited in 2008 following a 2000 split and released a greatest hits album titled "Back Again ... No Matter What."