Cox was born in Springboig, Glasgow in 1972.[1] He attended Saint Andrew's Roman Catholic Secondary School in the East End.[2] He then studied at Edinburgh’s Queen Margaret University School of Drama and trained as an actor, gaining a diploma in drama in 1993.[1][3]
Cox worked with the creators of Still Game in their successful sketch show Chewin' The Fat between 1999 and 2005.[4] From 2002 to 2019, he played Tam Mullen, a local miser in the BBC comedy sitcom Still Game.[5]
It was announced in 2006 that Cox would narrate the Roald Dahl favourite, Three Little Pigs. It made its stage debut at the Glasgow Royal Concert Hall, set to music by composer Paul Patterson.[6]
In 2007, Cox contributed as a writer to the tv show Dear Green Place.[7]
In autumn 2014 Cox rejoined the Still Game cast for a sell-out run of live shows in Glasgow at The Hydro which culminated in a final 2019 performance.[8] In 2019, he also played a senior Scottish Police officer in Only an Excuse?.[9]
He was awarded an Honorary degree for his contribution to Scotland’s drama and arts scene by his alma mater Queen Margaret University in July 2022.[3]
In January 2025, he co-hosted a Burns Night supper for Spina Bifida Hydrocephalus, which raised £96,000 in 2025 to support those affected.[10] In 2025, he played Duncan Finlay in Dept Q on Netflix, alongside Still Game co-star Sanjeev Kohli.[11] He also toured Scotland with a personal show, a mixture of comedy and personal reflection.[11][12]