The Campile native featured against Romania at RWC 2015 and went on to make his Six Nations debut the following spring, featuring off the bench against Wales. He replaced Mike Ross to help Ireland secure a famous victory over the Springboks in Cape Town in June 2016 and later that year would start in Chicago as Ireland recorded their first ever win over New Zealand.
He started every game of the 2017 Six Nations Championship and has gone on to win 19 caps for his country to date. Selected for the 2017 British & Irish Lions tour, Furlong was the starting tighthead for all three Test matches against New Zealand.

The 25-year-old front rower made his debut for his native Leinster against the Newport Gwent Dragons in November 2013 and has won 73 caps for the province so far, scoring four tries.

Tadhg Furlong said: "I am delighted to have signed a contract with the IRFU to continue to play with Leinster. I got a number of opportunities over the past few seasons that have helped me to develop as a player and I want to continue to develop and be successful with both Leinster and Ireland."
Mick Dawson, CEO of Leinster Rugby, added: "This is great news for Leinster and Ireland. Tadhg is a product of the Leinster Youths system and has come through New Ross, into our age-grade system, into our senior team and now to the highest honours with Ireland and the Lions.
"His signature is a huge boost as we continue to build for the coming seasons. Securing homegrown and young talent like Tadhg is a key part of the Leinster way."