The vocals were among the last recorded by Gately before his death
Boyzone have announced the release of their first song since the death of Stephen Gately.
Gave It All Away, which features the late singer's vocals, is due out on 1 March, to be followed by a new album, Brother, on 8 March.
Gately died, aged 33, at his Majorcan holiday home in October last year.
He sings the song's opening lines: "I will learn to live before I die". The accompanying video is "incredibly raw," said singer Ronan Keating.
It features archive video of Gately and his band-members, intercut with newly-filmed scenes of the group writing letters to their "other brother".
Keating, Keith Duffy, Shane Lynch and Mikey Graham are also seen shedding a tear for their former bandmate.
"It's us reminiscing about the good times and the laughter," explained Keating.
Keating described the video as "incredibly raw"
"There's a nice scene of us four brothers sat around a table... with Stephen's favourite picture hanging up behind us.
"Phil (Griffin, director) just filmed us fly-on-the-wall for that so it's just us as we are," he added.
"We wanted the footage to be as truthful and honest as possible based on how we were feeling and were reacting during the making of the video on that day," he added.
But Keating said the band "didn't want it being too mournful all the way through".
Vocals for the song, written by Mika, were recorded in the summer of 2009, following Boyzone's sell-out UK tour.
The Irish band have clocked up four number one albums, and 16 consecutive top five singles in the UK.
In October, a post mortem revealed Gately had died of natural causes.