*Club domestic league appearances and goals, correct as of 26 November 2024 (UTC) ‡ National team caps and goals, correct as of 14:39, 3 January 2024 (UTC)
After impressive performances with the Japan U-17 team, Kōki Saitō debuted on 21 July 2018 in a league match against FC Gifu.[2] On his debut, Saitō even had the chance to share the field with Kazuyoshi Miura, who is 34 years his senior.[3]
On 13 August 2024, Saitō joined EFL Championship club Queens Park Rangers on a season-long loan deal.[7] He made his debut with the club on 17 August, coming on as 67th minute substitute. In the 88th minute of the same match, he assisted Lyndon Dykes to earn 10-man QPR a draw away to Sheffield United.