Aaron Johnson was born April 30, 1983 in Port Hawkesburry, Nova Scotia. The fourth pick, 85th overall selection of the Columbus Blue Jackets in the 2001 NHL Entry Draft, Johnson is a graduate of the QMJHL.
An offensive defenceman, Johnson played four years in the QMJHL with the Rimouski Oceanic capturing a Memorial Cup title in 2000, before ending his junior career with the Quebec Remparts in the latter stages of the 2002-03 season.
In 2003-04, Johnson split his first professional season between the AHL's Syracuse Crunch and the parent club in Columbus. The following season Johnson spent his entire year with in Syracuse due a lock out before returning to split his season with Columbus and Syracuse in 2005-06.
Johnson was a mainstay in the Columbus Blue Jacket lineup in 2006-07 appearing in 61 games, while recording 3 goals and 10 assists. Following that season, Johnson was signed as a free agent by the New York Islanders in the summer of 2007. In New York, Johnson appeared in 30 games and was sidelined from 35 games with a sprained right knee. After the Islanders failed to qualify for the NHL playoffs, Johnson was signed as an unrestricted free agent on July 15, 2008 by the Chicago Blackhawks.