Organisers are hailing it as a major coup for both the festival and the city, given that T-Vital will be the band's only European date of the summer.
"Snow Patrol are huge favourites with the Tennent's Vital crowd," Nicola McCleery, head of marketing for Tennent's NI, said.
"They played our very first festival back in 2002 and blew everyone away with their headline set in 2006 - which has gone down in Tennent's Vital history as a truly seminal moment."
We can't wait to welcome them back to home soil for what promises to be a very special second day.
Snow Patrol will play at the event on 15 August - the day after fellow headliners and US rock giants Kings of Leon open the festival.
More top acts are also set to be revealed by organisers in the coming months.
Tickets for the Kings of Leon on Day 1 are on sale now, while Day 2 Snow Patrol tickets will go on sale on Friday 17 May.