Will Genia, one of the most decorated players in Australian rugby history, has announced his retirement at the age of 37.

The scrum-half, who became the 78th player to captain the Wallabies, represented Australia at three World Cups.

He appeared 110 times for his country over a 10-year international career, making him the seventh-most capped Wallaby of all-time.

"Thank you to the teams, my team-mates, coaches, teachers, friends and all the wonderful people in the game who helped me, guided me, shaped me, included me, put up with me and made me better," Genia wrote on Instagram.

"Thank you to the fans for making the game what it is.

"Finally - thank you rugby for all the joy. It was always the game and then everything else."

Genia became just the 10th Australian to amass 100 caps when he appeared against England at Twickenham in 2018.

The last of his 110 caps came in 2019.

Genia was nominated for the 2011 IRB Player of the Year award following his appearances at the 2011 World Cup, when Australia were beaten by rivals New Zealand in the semi-finals.

He finished his career with Japanese side Kintetsu Liners, following earlier spells with Stade Francais and the Melbourne Rebels.

"Will was a world class number nine who starred on international rugby's grandest stages for more than a decade," said Rugby Australia chief executive Phil Waugh.

"He has the rare distinction of having captained his country and played a leading role in some of his generation's most famous matches."