Born in Brighton and educated at Bromsgrove School,[2][1] Mullan made his Worcester Warriors debut against the Newport Gwent Dragons in the Anglo-Welsh Cup.

[6] In January 2019 Mullen retired from rugby citing a lack of motivation after a long spell out with injury.

[8] and was selected for the England Saxons against Ireland A in April 2009, though the game was cancelled due to poor weather conditions.

[9] Mullan did not tour in the summer of 2009 due to a shoulder injury,[9] whilst a torn hamstring thwarted a possible Senior debut in the 2009 Autumn Internationals.

[12] Mullan was called up to Eddie Jones' first squad for the 2016 Six Nations Championship in January 2016.