In 2001 he did a Master's in Film Production at Dublin Institute of Technology where he met Vicki Parks whom he later married.
While at university he directed several theatre productions including Arthur Miller's Death Of A Salesman, which was later staged at the Dublin Fringe Festival in 1999, produced by the actor Chris O'Dowd, the first of many collaborations between the pair.
That year he also won a National Student Drama Award for Best Film Script for Dead Leg, which he co-wrote with his brother Luke.
He worked as a staff writer on the TV3 series The Offside Show (2005), and directed and edited a short documentary, Big Massive Protest (2007).
The French/Irish/Swedish co-production was directed by Agnès Merlet, produced by Jean Luc Ormières, and featured actors Rachel Hurd-Wood and Harry Treadaway.
In 2010 he and Chris O'Dowd co-wrote a short film "Capturing Santa" as part of the Little Crackers series for Sky 1.
In December 2013, it was announced by Macmillan that O'Dowd and Murphy would be writing two children's books based on their award-winning series.
The series went into production in 2019 and Nick served as Head Writer/Executive Story Editor, leading a team of 19 writers in 4 countries across a total of 52 episodes.