Mr Barry claimed a seat for the Anti-Austerity Alliance-People Before Profit group in the competitive four-seater constituency of Cork North Central.
The first-time TD who became involved in socialism and political activism as a teenager was expelled from the Labour Party along with Clare Daly, Joe Higgins, and Ruth Coppinger for his membership of the Militant tendency in 1989.
In earning a Dáil seat he ousted outgoing Labour TD Kathleen Lynch.
“What I hope to do is to provide a strong radical left-wing voice for real change,” he told the.
“Areas such as low pay, the housing crisis, heath cuts and the abolition of water chares and property tax are important to me.”
Born in Columbus, Ohio, Mr Barry returned to Ireland in 1971 when he was eight, and grew up in Dublin’s Rathfarnham. However, the 52-year-old admits to having a “long-standing connection with Cork”.
“I decided to move down to Cork for six months in the early 90s and I stayed for 25 years,” said Mr Barry who lives in Blackpool with his wife Patricia.
First elected to Cork City Council in 2002, he helped increase support for the AAA grouping in Cork and the alliance managed to take three seats in the council elections in 2014.
This was Mr Barry’s fourth time to run in a general election and he is now ready to take on the challenge of national politics.
“It’s a new job, a new challenge but the message will remain the same, we just have a bigger platform,” said the Manchester United fan.
During the election campaign he set out to target the seat of sitting TD and junior minister Kathleen Lynch, which in the end proved a successful manoeuvre.
He was elected on the seventh count.
He said: “We had been campaigning away for many years but the water charge issue gave our campaign an extra boost.
“Going into the election we were seriously challenging for a seat and that increased as the campaign carried on.
“AA-PBP wants to replace the Labour party and build a new radical left who will not sell out.”
He now joins the five other members of the AAA-PBP elected to Leinster House including two other first timers — Gino Kenny of Dublin Mid-West and Bríd Smith who claimed a seat in Dublin South Central.