Australia's greatest Olympian, Emma McKeon, has announced she is retiring from competitive swimming.

McKeon, who won 14 medals across three Olympics, including a record six golds, announced on Instagram that it was time to step away from the pool.

The 30-year-old had already announced that Paris would be her final Olympics.

"Leading into Paris, I knew it would be my last Olympics, and the months since have given me time to reflect on my journey, and think about what I wanted my future to look like in swimming," McKeon wrote.
 
"I am proud of myself for giving my swimming career absolutely everything, both physically and mentally.

McKeon sits atop the table for the most medals won at the Olympics by an Australian, ahead of Ian Thorpe and Kaylee McKeown with nine medals each.

Her six golds also see her sit at number one in Australian Olympic history, ahead of Thorpe, McKeown, and Mollie O'Callaghan.

Comments on McKeon's post started to flood in after her announcement.

"So proud of you Em you're a legend in and out of the pool forever," Ariarne Titmus wrote.

"Love your work, Emma. Enjoy the next chapter," tennis legend Ash Barty posted.

"Incredible. What a career, proud to have shared a few teams with you. Congrats Emma, enjoy whatever is next," Paris gold medallist Jess Fox wrote.

McKeon told ABC Illawarra in August that she had a complicated relationship with the sport that made her a global star.

"It is a love hate relationship with a lot of it, but once it is not there you realise how good it is and you really miss it," she said.

"Even when I'm on break, I always feel like I am missing pushing myself and working towards a goal."