Alistair William Johnston (born October 8, 1998) is a Canadian professional soccer player who plays as a right-back for Scottish Premiership club Celtic and the Canada national team.

He later had spells with Major League Soccer teams Nashville SC and CF Montréal before signing for Celtic in late 2022.

[6][7] In 2015, he joined Vaughan SC, helping them win the 2015 U-18/U-19 Disney Soccer Showcase, the 2015 OYSL U-18 League title,[8] and the 2016 and 2017 U21 Ontario Cup.

[19] He made his debut for Montreal on February 23, as a substitute against Liga MX side Santos Laguna in the club's second leg of their 2022 CONCACAF Champions League tie.

[21] In December 2022, CF Montréal announced they had transferred Johnston to Scottish Premiership side Celtic, taking effect January 1, 2023.

[23] Upon the announcement, Johnston stated at a press conference that former Celtic and current CF Montréal midfielder Victor Wanyama was a major influence on his decision to move to the Bhoys.

[24][25] Johnston made his debut for Celtic on January 2, starting against rivals Rangers and playing the entire match in a 2–2 away draw.

[39] Johnston's younger brother, Malcolm, is also a soccer player and was selected in the first round of the 2023 MLS SuperDraft by New York City.