Johnson was a key member of Melbourne's team of 2007, making an average of 36 tackles a match. Melbourne won the season's grand final against the Manly-Warringah Sea Eagles, but in 2010 were stripped of their premiership after the NRL discovered large-scale breaches of the league's salary cap. Johnson's 2007 form was rewarded by his selection in the Australian Kangaroos team for a Test against New Zealand in October. In the same season, he made a record-breaking 62 tackles in Queensland's victory over New South Wales in the second match of the State of Origin series. In the third match, he was taken from the field in the first half after suffering a concussion. Queensland's medical staff controversially allowed him to return to the field in the second half, where he make 25 tackles.