Johnson added to her Paralympic medal collection at London 2012 Paralympics, as she set a new Paralympic record en route. Johnson recorded a season's best time of 1:40.90, to take the bronze medal in the SB6 100 m backstroke. In the buildup towards her fourth Paralympics at Rio, Johnson underwent an operation for a hernia. While recovering, she found herself falling behind in her training, which impacted on her preparation for the 2016 Paralympic trials. Her failure to make the trials resulted in her decision to retire from competitive swimming.