Born in
Bamawm, Victoria, McMahon captained the
Melbourne Vixens in the
ANZ Championship and played 11 seasons for the
Melbourne Phoenix (as a captain for four seasons) in the previous
Commonwealth Bank Trophy. She led the Vixens to the ANZ Championship title in 2009, defeating the
Adelaide Thunderbirds in the grand final. McMahon captained the Vixens from its inaugural season in 2008 until 2011, sharing the captaincy with
Bianca Chatfield from 2009. McMahon was best and fairest for the Vixens in 2009 and 2010, having previously been voted best and fairest for Melbourne Phoenix four times between 2000 and 2007. On 31 March 2011, McMahon ruptured her Achilles tendon in an ANZ Championship game against
Queensland Firebirds. Following surgery, she withdrew from the
2011 Netball World Championships in
Singapore, and was considering her playing future. Australian coach
Norma Plummer described McMahon as "probably the most athletic player of natural talent" to have played the game. McMahon confirmed during the off season that she would be returning to the
Melbourne Vixens in the 2012
ANZ Championship. But after playing one pre season match McMahon announced that she was pregnant and withdrew from the Vixens team for the 2012 season. Her son Xavier was born on 30 August 2012 and her daughter Ruby was born on 27 November 2015. On 25 October 2012 it was announced that McMahon would return to the Melbourne Vixens for the 2013 season. McMahon officially retired at the end of the 2013 season. At the end of each season, the Melbourne Vixens' most valuable player is awarded the
Sharelle McMahon Medal. In 2017 McMahon joined the match review panel of the
AFL Women's football league in its inaugural year. ==International career==