Allen debuted as a teenager for the
Otago Nuggets in 1998 and enjoyed his best season with the club in 2001, when he averaged 20 points per game and was named in the
All-Star Five. His first championship title came the following year in 2002 with the
Waikato Titans. He returned to Otago for the 2003 and 2004 seasons before joining the
New Zealand Breakers as a development player for the
2004–05 NBL season. He went on to play three seasons for the
Harbour Heat while also joining the
Singapore Slingers for the
2007–08 NBL season. In 2009, Allen joined the
Auckland Stars before returning to Waikato to play with the Pistons in 2010 and 2011. Allen's second championship came in 2012 with the
Auckland Pirates. In 2013, Allen returned to Otago to play for the Nuggets once again. After taking a year off from basketball, Allen signed with the
Super City Rangers for the
2015 NBL season on 1 December 2014. On 1 April 2016, Allen signed with the
Southland Sharks for the rest of the
2016 NBL season. On 25 January 2017, he re-signed with the Sharks for the
2017 season. Allen battled a groin injury for much of the 2017 season. On 22 November 2017, he re-signed with the Sharks for the 2018 season. However, he later retired prior to the start of the season. ==National team career==