Colm was born in Dublin and raised bilingually through Irish and English. Over the past fifteen years he has directed a number of multi-award-winning short films and many hours of documentary television for RTÉ, TG4 and TV3/Virgin Media. These include the four-part IFTA-nominated series The Joy (TV3), the award-winning feature-length drama documentary The Maamtrasna Murders (TG4), the IFTA award-winning docudrama Cumann na mBan – Women of the Revolution (TG4) and the IFTA-nominated documentary Frank O’Connor – Idir Dhá Shruth. Colm’s 2013 fly-on-the-wall doc series An Ceoldráma (The Musical) was nominated for three IFTA Awards, including Best Director.

In 2012, Colm received a distinction from the Screen Director’s Guild of Ireland for his contribution to Irish-language film-making.

Colm made his narrative feature debut with An Cailín Ciúin (The Quiet Girl), an adaptation of Irish author Claire Keegan’s celebrated story, Foster. The film premiered at the 72nd Berlinale where it won the Grand Prix of the International Jury of the Generation Kplus programme. It opened the 2022 Dublin International Film Festival, winning the Audience Award and the Dublin Film Critics’ Circle Award for Best Irish Film. Colm also received an Aer Lingus Discovery Award during the festival. The film scooped 7 Irish Film & Television Academy Awards including Best Film, Best Director and Best Actress. Colm was also the recipient of the Screen Ireland-IFTA Rising Star Award. In its opening week of release in Ireland and the UK, the film became the highest-grossing Irish-language film of all time.