The 46-year-old has been tasked with pepping up the Scotstoun side’s attack as they prepare for their first season in the new United Rugby Championship.
Danny Wilson, the Warriors head coach, lost No 2 Jonny Bell to Worcester at the end of the season after his family failed to settle in Scotland.
Carolan, who has been Connacht’s attack coach since 2017, said Glasgow’s style suited him.
“Glasgow Warriors play an exciting brand of rugby that fits perfectly with my own philosophies on how the game should be played,” he said.
“The squad consists of world-class players and some really exciting up and coming young players. Helping those players realise their potential is something I will take a lot of pride in.
“I’m really looking forward to challenging myself in this new environment, learning from others and enhancing Glasgow’s attack.”
Carolan was head coach of Ireland Under-20s from 2014-17 and led them to the final of the World Rugby U20 Championship in 2016, beating New Zealand in the group stage before losing to England in the final.
He played for Connacht on the wing but his career was cut short by a neck injury at 26.
Wilson described Carolan as “a very technical coach” and said: “Connacht have had a great attack for a number of seasons and Nigel’s work has been a massive part of that.
“He is a very technical coach who really impressed us with his passion and experience not only in coaching a successful attack but also developing young talent.”