 Johnson was a member of all New Zealand wheelchair rugby teams from 1998 until 2010, including the gold medal-winning team at the 2004 Summer Paralympics in Athens and the bronze medal-winning team at the 2000 Paralympics in Sydney.At the 2008 Paralympics, he was both a player and assistant coach for the New Zealand team, which finished in fifth place.He won silver at the world championships in Toronto in 1998 and in Christchurch in 2006, and was captain of the 2006 team.