[3] He joined Motherwell's academy aged 10, and progressed to the first-team, appearing in the matchday squad as an unused substitute for a 1–0 defeat to Kilmarnock on 26 December 2018.
[6] McKinstry made his Premier League debut for Leeds on 21 November 2021 as a second-half substitute in the 2–1 defeat to Tottenham Hotspur.
[7] On 13 June 2023, Leeds United announced that McKinstry's contract would not be extended at the end of the 2022-23 season.
[8] On 17 August 2022, Motherwell announced the return of McKinstry to the club, on a season-long loan deal from Leeds United.
[9] On 3 October 2023, McKinstry joined Scottish Championship club Queen's Park on a contract until the end of the season.