A solid utility player Mulligan is most often used at left or right back but is more than capable of impressing in a midfield role with the 28-year-old also known as a dead-ball specialist with an eye for goal.

Along with Ben Sigmund, Mulligan was the only player to appear in all six of New Zealand’s FIFA World Cup qualifiers™ in the Oceania zone, scoring three goals in the process. This followed a lengthy absence from the national team set-up for Mulligan who debuted in 2002 after progressing through New Zealand's national youth teams.

Born in Liverpool, England, Mulligan has played for several clubs in that country including Barnsley, Port Vale and Doncaster Rovers and most prominently, Scunthorpe United, who he helped achieve promotion to the Championship in 2006.

Following a career of almost 200 first-team appearances in England, Mulligan returned to New Zealand to join a number of national team colleagues at Wellington Phoenix under Herbert. Mulligan started New Zealand's first two matches against Spain and South Africa at the FIFA Confederations Cup South Africa 2009 but since then his career has been on a downhill slide. Despite regular appearances in the All Whites squad over recent years, Mulligan made only three starts for the Phoenix in two seasons and his contract was not renewed at the conclusion of the season in March.