On 18 May 2014, Hammett was named Director of Rugby for Wales-based team Cardiff Blues, working alongside Dale McIntosh and Paul John. The Mark Hammett era was a slow start, losing both the pre-season friendlies. However, the first round saw Cardiff defeat Zebre 41–26. Despite only winning one game in his first competitive 6 games, Hammett lead Cardiff to a surprise victory over French side Grenoble and an easy victory over Rovigo Delta in the 2014–15 European Rugby Challenge Cup. These games were backed-up by a narrow loss to Irish giants Munster. On 24 January 2015, Hammett led the Blues to an away victory over Grenoble, to see the side through to the quarter-finals of the 2014–15 European Rugby Challenge Cup. On 20 February 2015, Cardiff were beaten by Benetton Treviso 40–24 in Treviso, which later turned out to be Hammett's last game in charge of the Welsh side. On 25 February 2015, after six months of a three-year contract, Cardiff Blues agreed to release Hammett at his request for personal reasons, to allow him to return home to New Zealand.