[1][6] Rankin began his professional career in 2006 by starring alongside Robert Florence in VideoGaiden, a Scottish video game show originally aired on BBC Two Scotland.

[12][13] Two years later Rankin was cast as lovelorn Army Captain Thomas Gillan, alongside Kevin Doyle and Oona Chaplin, in the WWI based mini-series The Crimson Field .

[19][20] Writer Kay Mellor tailored the role of Sean McGary for Rankin, changing the character from a Northerner to a Scot, in 2015's third series of her anthology drama The Syndicate.

[22] That same year, BBC One's four part crime drama From Darkness saw Rankin portray Norrie Duncan, husband to Anne-Marie Duff's ex-Manchester cop Claire Church.

[31][32] Series twenty of ITV's long-running crime drama Midsomer Murders, which premiered in the United States in 2018 prior to its release in the UK, featured Rankin in episode four as rugby star Danny Wickham.

[35] In July 2020, Rankin starred in an episode of the National Theatre of Scotland/BBC Scotland's Scenes for Survival, a series of short theatrical productions that were filmed in quarantine, which was created in response to a worldwide outbreak of COVID-19.

[45] Returning to short films in 2016, Rankin starred as Vance in Chloë Wicks' The Wyrd, the story of a young couple in seventh century pagan England dealing with the introduction of Christianity.

[46][47] It was announced in 2021 that Rankin would star in the short film Hello, Muscles, alongside Game of Thrones alumna Kate Dickie, as part of a campaign to raise awareness for young carers (caregivers).

[48][49] In 2008, while still in school at Langside College, Rankin portrayed Bothwell in Liz Lochhead's play Mary Queen of Scots Got Her Head Chopped Off at the Citizen's Theatre in Glasgow, Scotland.

[1][61] In 2014 he would headline in Kieran Hurley's play Bruises, part of the Royal Court Theatre's Unusual Unions series, as one of two brothers with diametrically opposing views meeting after a long absence.

[66] Rankin appeared as Jack in BBC Radio Scotland's four-part Saddled in early 2019, a comedy which revolved around the adventures of The Easy Rider Cycling Club's members.