McMillan made his screen debut in David MacKenzie film Outlaw King alongside Chris Pine.
[1] He appeared in the award-winning short film Mind Yersel, by writer and director Bonnie MacRae, showing the reality of male suicide in Dundee, dubbed the ‘Scotland’s suicide capital’.
[2][3] In 2021, he appeared as Jamie in the Stephen Graham restaurant based drama film Boiling Point,[4] and reprised the role in the 2023 television series sequel of the same name.
[5] In 2021, he could also be seen as a vulnerable cabin boy in the BBC Two adaptation of the arctic whaling drama series The North Water alongside Colin Farrell and Stephen Graham.
[6] Film appearances in 2023 included Lynch in the Irish Republican Army drama Dead Shot, and as Richard E Grant’s son Bertie Sinclair in The Lesson.