Lierse Sels started his youth career at Kontich, and transferred to
Lierse at the age of seven. Over there, he made his first-team debut in 2010. After the departure of
Eiji Kawashima to
Standard Liège in the summer of 2012, Sels became the first choice keeper. In his first game in the First Division, on 29 July 2012 against
Gent, he saved a penalty. At the start of the 2013–14 season, when he refused to sign a new contract, he was demoted to the second team.
Gent in 2015|259x259px On 31 December 2013, it was announced that Sels would complete a transfer to
Gent once the transfer window opened. He would become the number one goalkeeper as
Frank Boeckx's contract was due to expire at the end of the season. Sels made his debut for Gent on 14 January 2014 against
K.V. Kortrijk, in the quarter-finals of the
Belgian Cup. He helped Gent qualify for the next round after penalties; with the game ending 1–1 on aggregate. Sels played a key role in helping Gent become champions of the
2014–15 Belgian Pro League, the first national championship in the club's history. This triumph allowed Gent to qualify for the
2015–16 UEFA Champions League. On his Champions League debut Sels dramatically saved an
Alexandre Lacazette penalty to help his side secure a 1–1 draw with
Lyon. On 13 January 2016 he was voted
Best Goalkeeper of Belgium 2015.
Newcastle United On 29 June 2016, Sels completed a transfer to
Premier League club
Newcastle United on a five-year contract for a reported transfer fee of £6.5 million. Sels made his Newcastle debut in the
Championship on 5 August against
Fulham. Sels kept a run of four clean sheets spanning 20 August to 13 September. Sels came under considerable fire from Newcastle fans for allowing a late equaliser from
Aaron Tshibola at
Aston Villa on 24 September. Despite receiving endorsement from manager
Rafa Benítez during the week, Sels lost his place in the line-up to
Karl Darlow against
Norwich City on 28 September. His displacement from the line-up also received notable media coverage in his native Belgium. When Newcastle's next League Cup tilt came up, it was Sels who got the start, enjoying a clean sheet in a 6–0 victory over
Preston North End on 25 October. On 22 June 2017, Sels signed for
Anderlecht on a season-long loan.
Strasbourg On 27 July 2018, Sels moved to
Ligue 1 side
Strasbourg for £3.5 million. In his first season at the club, he was awarded Strasbourg's player of the Season.
Nottingham Forest in 2025.|259x259px On 1 February 2024, Sels moved to
Nottingham Forest. He made his Premier League debut for Forest 3 days later, in a 1–1 draw away to
Bournemouth. On 2 March, Sels made a point-blank save in a match against
Liverpool that earned him the
Premier League Save of the Month award. By achieving that honour, he became the first ever Nottingham Forest player to win a Premier League monthly award. Following the
2024–25 season, Sels was the first Nottingham Forest goalkeeper awarded the
Premier League Golden Glove, shared with
Arsenal's
David Raya, after achieving 13 clean sheets. ==International career==