One of the most versatile players in the 2010 NAB AFL Draft, Johnson was selected at number 57 by the Swans following a strong year with both the Oakleigh Chargers and Vic Metro. Johnson made his debut in Round 3 of the 2011 season, playing 20 games in his first year including two finals. Johnson was the second youngest player to take the field in the 2012 AFL Grand Final where he showed poise and maturity beyond his years across playing an integral defensive role in the Sydney Swans 5th VFL/AFL Premiership. Since the 2012 AFL Grand Final, Johnson has battled a series of serious knee injuries that have prevented him from adding to his tally of 45 games for the Swans. On the eve of the 2015 season, Sydney Swans Co-Captain Jarrad McVeigh paid tribute to Johnson, who he described as an inspiration to the entire club. Johnson is expected to return to field for the 2016 season.