The backrower burst onto the International arena in 2017 following a man-of-the-match display in just his sixth Test match before injury cruelled his 2018 season.
Dempsey said: “I went a long time without any good news so now to have some back-to-back good news after playing the last game and to now re-sign, is just awesome.
“Firstly to stay in New South Wales is great but then to have the opportunity to represent Australia for potentially the next two years is just a cherry on top.
“The support I’ve had from the Waratahs and the Wallabies over the past year has been world class so I have to thank them so much for helping me get back to this level,” Dempsey said.
Qantas Wallabies coach Michael Cheika said: “He’s a tough guy, you can see that in him. He’s got a real thirst for it. He wants to play footy, he wants to try and be the best he can be.
“I’m getting to know him better and better but I can already see he’s hungry to play and that’s the number one prerequisite for good footballers is that they want to play at all costs,” Cheika said.
Dempsey is a graduate of the Australian Rugby pathway after being selected for Australian Schoolboys side in 2011 before playing for the U20s in 2014.
A Super Rugby debut for the Waratahs came the following year before Dempsey was selected in Michael Cheika’s 2016 Spring Tour squad as a Development Player.
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