A former pupil of Coleraine Inst, Andrew joined Ulster Rugby on a development contract at the start of the 2004-05 season aged 19.

However, the 2005-06 season was to be the year he would come to prominence on both a provincial and international stage. He made his Ulster debut against Cardiff at the Arms Park in the first Celtic League match of the 2005-06 season and despite having just 8 Ulster caps under his belt he made his international debut for Ireland in November 2005, winning his first cap against Australia at Lansdowne and scoring a brace of tries against Romania the following week.

Andrew is now a regular in both the Ulster starting XV and the Ireland squad. He featured for Ireland in four out of their five 2006 Six Nations matches and in June 2006 he toured New Zealand and Australia with the squad starting all three tests.
His fantastic season finished with Andrew winning the Ulster Player of the Year award at the 2005-06 Ulster Rugby Awards and becoming a firm crowd favourite.

Winning 19 Caps with Ulster Rugby last season Andrew displayed his versatility in 2006/07 by playing either Centre or on the Wing. He continued his international career being selected for Ireland v South Africa in the Autumn Internationals and later the 6 Nations Squad. Andrew was selected for the Argentina tour June 2007 he was unlucky to pick up an injury forcing him to only feature in 1 game.