He started his career with a bang, kicking 3 goals on debut for the Magpies, however, he settled as most first-year players and struggled to play-out in consistent fashion, being dropped mid-season.

In 2005 he had an interrupted season, with injury concerns after a concussion mid-season, and also a rumoured dispute with coach Mick Malthouse.

Johnson continued his form consistently through the season, giving him another second place in the Copeland Trophy and averaging more than 23 disposals.

In Round 20, 2007, Johnson received a six match suspension for making forceful front-on contact with Melbourne's Daniel Bell which ended his finals campaign.

His career was on the rocks in 2008 before rebounding to reach some of his best form in the latter stages of 2009 despite suffering a broken leg in the round three loss to Geelong.

Johnson was later charged with recklessly causing injury and unlawful assault and appeared before a Magistrate in 2007 but avoided conviction due to his heavy involvement in community service with the TAC.