Duffy began his career as a youngster with Everton, where he made ten senior appearances. He made his Blues debut in the Europa League against AEK Athens in December 2009.

At Goodison Park he had loan spells with Burnley, Scunthorpe United and Yeovil Town, clocking up 50 senior appearances, with the majority coming in the Championship.

He played international football for Northern Ireland from under-16 to under-21 level; and in 2010 he opted to represent the Republic of Ireland, initially playing for the under-21s.

Called up to the senior squad in 2012, he eventually made his senior debut against Costa Rica in June 2014.

In September that year, he moved to Blackburn Rovers for an undisclosed fee. He made 69 appearances for the Ewood Park club, scoring seven goals.

He was part of the Ireland squad at Euro 2016, helping them to a famous 1-0 win over Italy and qualification for the last 16.

Albion's then record signing made his league debut against Newcastle United at St James' Park and hit his first goal for the club against his former employers at Ewood Park, before sealing promotion to the Premier League.

Duffy missed just one match during the 2017/18 campaign, and continued his impressive partnership alongside Lewis Dunk to help the Seagulls secure their top-flight status for another season.

The Irishman has a club record to his name, after beating Gerry Ryan's and Steve Penney's cap haul whilst playing for the Seagulls.

Duffy signed a new contract alongside Lewis Dunk in October 2018, and has now committed his future to the club until June 2023.

He spent the 2020/21 season on loan with Celtic, making 27 appearances in all competitions.

He returned to Albion and put in a Man of the Match performance on his first Albion start in nearly 18 months in a 2-1 win at Burnley on the opening day of the 2021/22 season.