Furlong started his youth career at St. Joseph's Boys based in Dublin, before joining Bray Wanderers and then Shamrock Rovers in 2017, where he made his senior debut in April 2019, aged 16.
[2] In July 2019, Furlong joined academy of Premier League side Brighton & Hove Albion.
[3] He made his professional debut for the first team on 24 August 2022, appearing as a 85th-minute substitute in the 3–0 away win at League One side Forest Green Rovers in the second round of the EFL Cup.
[4] On 31 January 2023 on transfer deadline day, Furlong signed for Scottish Premiership side Motherwell on loan until the end of the season.
[5] Furlong signed for EFL Championship side Hull City for an undisclosed fee on 1 September 2023.