Stirling is one of Ireland's most-experienced players, capped 117 times in ODIs and 78 times in T20Is, as well as playing all three Tests since the country's elevation to Full Member status. He is their leading run-scorer in both white-ball formats, and his 177 against Canada in 2010 remains an ODI record for Ireland.
The two former Middlesex team-mates, who lived together during their time in London, will now oversee Ireland's fortunes as they attempt to build for future challenges, including a T20 World Cup and the new 50-over World Cup Super League.
"It was fitting to get a call from Bal to ask me to be his vice-captain," Stirling said. "We've played together all the way up from when we were kids so I look forward to helping him shape the way this Irish side moves forward in the coming months and years ahead.
"He's had an excellent start to his captaincy with wins in the Caribbean and the subcontinent, but there is so much on your plate as captain - especially with a younger team than we've had in the past - so I am happy just to be a sounding board to bounce ideas off and help implement any changes in the way Bal wants to take this team forward on and off the field."
Stirling recently moved back to Belfast, after losing his status as a non-overseas player in county cricket. His first assignment as Balbirnie's deputy could come in England, with discussions still taking place over Ireland's proposed visit for three ODIs at the end of next month.
Balbirnie took over as Test and ODI captain from the long-serving William Porterfield in 2019, before being given the T20I role as well. Ireland have lost six out of eight completed matches this year, but pushed West Indies close in the second ODI at Bridgetown before winning a T20I in Grenada.
"I've known Paul since I was about 12 years old when we first played against each other in inter-provincial cricket - we've grown up together in our careers as such," Balbirnie said. "We both went to Middlesex at the same time and lived together over in London, so he's someone I consider a very close mate but also a very valuable person to have in our side from a knowledge point of view. So I didn't really hesitate when I was thinking about who could be my vice-captain - he stuck out to me straight away.
"I first mentioned the idea to him in the Caribbean and he said he'd love to do it. He's someone that I've always sought advice from when thinking about my batting, so to have him as my right-hand man over the next few years is really exciting and one I'm sure he's excited for as well.
"I think within the Irish squad we have a lot of experienced guys to be able to voice their opinion, but at the end of the day, it is my decision. To have different points of view is great and refreshing, but with someone like Paul he is someone I'd talk to a lot about the game - it's exciting for the next phase of the squad we're bringing through. Even for the young players, to have someone like Paul to have a chat to in the change room or at training, he's valuable to us both on the field and off."