McMahon said two moments with the national team, both against arch-rivals New Zealand, stood out.
"I always find it really hard to pinpoint things, but two experiences with the Diamonds, winning the world champs in 1999 and winning the Commonwealth Games gold medal in Manchester (in 2002) in double extra time were two real highlights from the Aussie team," McMahon said.
"It's hard (to choose highlights) from a club perspective because it was all so different.
"But certainly the 2009 premiership with the Melbourne Vixens was a really special one with how we actually got there and achieved what we wanted to achieve as a team."
McMahon said it was a tough decision to retire as she still loved the game but it was no longer as great a priority in her life as it has been.
"I have kind of just felt like my really strong desire and passion I have always had to put netball first and put everything into that was just not there as it used to be and that, for me, was enough," McMahon said.
McMahon was also last week left out of Australia's 17-strong squad to play Tests against New Zealand and Malawi.
-AAP