Celtic

Dembélé started playing football for Park Villa Boys Club at the age of five and was recognised as a prodigy from a young age.^[5] He joined Celtic aged 10 in 2013.^[6] In July 2016, Dembélé was named as player of the tournament when representing Celtic under-13s at the St Kevin's Boys Academy Cup.^[7] Soon after his appointment as Celtic head coach, Brendan Rodgers invited Dembélé to participate in a light technical training session with the first-team squad.^[8][9]

On 3 October 2016, Dembélé gained widespread media attention after making his debut for Celtic's under-20 side aged 13 playing with and against players who were up to seven age groups above him.^{[10][11][12][13][14][15]} He was named on the bench because several regular starters were away playing for Scotland's under-19 team and was brought on during the 81st minute, replacing the youngest first-team player in Celtic's history, 16-year-old Jack Aitchison.^[16] A match report on the official Celtic website stated that "the diminutive playmaker didn't look out of place and played his part in the closing stages."^[17] The response to Dembélé's under-20s debut included concern about the physical and mental impact of such a young player being fast-tracked through the developmental ranks.^{[8][18][19][20][21]} On 2 June 2017, Dembélé signed a youth registration contract to stay at Celtic.^[22]

On 24 December 2018, aged 15, Dembélé signed his first professional contract with Celtic, set to keep him at the club until 2021.^[23] In April 2019, he featured for Celtic's academy team in the seasonal finals of both the Scottish Youth Cup and the Glasgow Cup, losing out 3–2 to Rangers in the first^[24] and beating the same opposition by the same scoreline in the second.^[25]

Dembélé made his senior debut on 19 May 2019 in a 2–1 victory against Hearts, coming on as a second-half substitute. After the match, Dembélé collected his winners' medal and helped to lift the Scottish Premiership trophy as Celtic ended the season nine points clear at the top of the league.^[26] His performance was praised by manager Neil Lennon.^[27] Six days later, Dembélé was named in the squad for the 2019 Scottish Cup Final, also against Hearts. This time he did not leave the bench, but collected a winners' medal following Celtic's 2–1 victory.^[28] In October 2019, L'Équipe named Dembélé as one of six "outstanding young players set to revolutionise the game", a list that also included Barcelona's Ansu Fati.^[29] On 12 December 2019, Dembélé became the youngest-ever footballer to play for a Scottish team in European competition when he came on as a substitute in Celtic's 2–0 loss away against Romanian side CFR Cluj.^[30]

Dembélé rarely featured for the first team after that,^[31] but he did come on as a substitute against St Johnstone on 12 May 2021, and scored his first senior goal in a 4–0 win for Celtic,^[32] latching onto a pass from David Turnbull and scoring from a tight angle.^[33] He sustained a fractured ankle during a pre-season friendly against Bristol City in July 2021, and eventually had to undergo an operation in October 2021.^[34][35] He made his return to action on 13 February 2022, playing in Celtic B's 4–0 win over Vale of Leithen in a Lowland Football League fixture.^[35] After being an unused substitute in three first-team games,^[36] as well as scoring for the B side in a Glasgow Cup tie against Queens Park,^[37] Dembélé finally returned to first-team action on 2 March 2022, when he came on as a substitute for Jota near the end of Celtic's 2–0 win over St Mirren.^[36]

Brest

Having left Celtic after nine years, following the expiration of his contract, Dembélé joined French club Brest on a free transfer on 5 July 2022, signing a four-year contract with the Ligue 1 side.^[38][39][40]