She was born without her left forearm.Cunningham first swam in international competition at the age of 13, at the 1990 World Games for the Disabled in Assen, The Netherlands.
At the 1992 Summer Paralympics, Cunningham won the Women's S9 50m freestyle event in what was then World Record time.
She won silver medals in 100m freestyle, 100m backstroke, 4 × 100 m freestyle relay and 4 × 100 m medley relay events.
She competed at the 1996 Summer Paralympics but did not win a medal.
She retired from swimming after the Atlanta Paralympic games.In 2006, Cunningham turned to triathlon.
Initially competing in age-group races against non-disabled triathletes, she discovered paratriathlon in 2009.
Classified as a TRI-4 (arm-impaired) paratriathlete, she became the 2009 ITU European Paratriathlon Champion and 2009 World Paratriathlon Champion in her class.
She placed second at the ITU World Paratriathlon Championships in 2010, 2011 and 2012.In late 2012, Cunningham was elected to the International Triathlon Union Athletes Committee.
She and South African Oswald Kydd, elected on the same day, are the first-ever paratriathlete representatives on the ITU Athletes Committee.Cunningham competed in paratriathlon at the 2016 Summer Paralympics in the PT4 category and finished seventh.