Jason Kerrison, the front man for OpShop. The group last performed together in 2013.
OpShop say their kids are to blame for their first performance in more than four years.
"A few of us have kids who have not seen us play before and they have little idea about what it's all about," the Kiwi rock group's guitarist Matt Treacy says.
"It will be great to have them side of stage for the first time."
OpShop, led by front man Jason Kerrison, has confirmed it will reunite to perform at Homegrown on April 7 in Wellington next year.
The all-Kiwi line-up also features performances by Dave Dobbyn, Devilskin, Che Fu & the Kratez, Anika Moa, Aaradhna, Hollie Smith, The Feelers, Savage and David Dallas.
The news ends OpShop's hiatus, which was confirmed by Kerrison in 2013 after a run of three popular albums including 2010's No. 1, Until the End of Time.
Their singles include One Day, Maybe, No Ordinary Thing and Love Will Always Win.
Treacy said the festival had asked them to perform several times over the past few years, and when they got the call this time the band decided the timing was right.
OpShop, also including drummer Bobby Kennedy and bassist Clint Harris, haven't decided if the one-off show would lead to a full reunion or the release of new music.
Treacy admitted the band's four members hadn't "been in the same room together" since going on hiatus.
"I think there is a bit of nervous energy mounting about getting back in the room together and seeing how it all sounds with no expectations of anything past this gig," said Treacy.
But he admitted "there is a growing appreciation of what Opshop was and what we achieved".
He also said: "Who knows what the future will bring."
OpShop is the latest of several Kiwi acts to reform recently, including Stellar, Zed and Elemeno P, who reformed for last year's Homegrown festival.
Who: OpShop
Where and when: Performing at Homegrown on April 7
More information: www.homegrown.net.nz
Telegraph: Who are the new ‘It Boys’ – and why can’t anyone else get lucky?