[4] In Espoo, Kamara had played football in the youth sectors of Olarin Tarmo –77 in Olari, and in Espoon Palloseura (EPS) in Espoonlahti.

[5][6] Kamara continued his career in England for Sunday side Westway of Ladbroke Grove,[7] before moving to the Southend United youth system and then on to Arsenal in 2012.

[9] Kamara made his only appearance for Arsenal a day before his 20th birthday on 27 October 2015, up against Sheffield Wednesday in the EFL League Cup fourth round in an eventual 3–0 away loss; he started the match and was substituted for Krystian Bielik after an hour.

On deadline day of the summer transfer window, 31 August 2016, Kamara joined Colchester United in League Two on loan until January 2017.

[14] He made his debut for the club in a Scottish League Cup game away to Raith Rovers where he put in a man of the match performance.

[18] On 18 March 2021, Kamara accused Slavia Prague player Ondřej Kúdela of racist verbal abuse during a Europa League knockout match.

[24] Days later, he was sent off away to Sparta Prague, a game in which his every touch was booed by the mostly underaged audience in relation to the Kúdela abuse; UEFA found insufficient evidence of a racial motive and did not punish the club.

Kamara made his debut for Leeds in the EFL Championship on 2 September 2023, as a late substitute in a 0–0 home draw against Sheffield Wednesday.

On 16 July 2024, Kamara joined Ligue 1 club Rennes[34] for a reported €10 million fee,[35][36] signing a deal until June 2028.

[34] He made his official debut in Ligue 1 with his new club on 18 August 2024, in a season opening game against Lyon, playing full 90 minutes and helping his side to a 3–0 home win.