Mark directed several television shows in the United States and the United Kingdom, many of them for the BBC. Mark co-produced the HBC television series Entourage, on which he was also a regular director.
Prior to Entourage, Mark's credits included the feature films Ali G Indahouse, The Big White, and What's Your Number? and the series Cold Feet, The Royle Family, and Bang Bang, It's Reeves and Mortimer.
Mark directed and executive-produced the pilot episode of the US version of the dramedy Shameless and also a couple of episodes of the UK version. He remains a co-executive producer and frequent director on the US series.
In 2011, Mark directed and executive-produced the pilot of the ABC fantasy series Once Upon a Time.
He worked on the 2011 romantic comedy What's Your Number?. The film received mixed revies. Mark is currently working on Game of Thrones.