Club captain Dave Dennis will end his lengthy association with the Waratahs at the end of this year's Super Rugby season to join Premiership side Exeter Chiefs.
Versatile forward Dennis, capped 18 times by Australia between June 2012 and November 2013, has agreed a three-year deal at Sandy Park.
"It was a really hard decision because I've been here my whole career," Dennis told the Waratahs' official website.
"I've spent 10 years here. I could easily stay here until my career ended but I've always wanted to challenge myself in a different environment.
"I'm not getting any younger and I think with the transition of Michael [Hooper] going into captaincy, I'm really comfortable with the way I'll be leaving the club at the end of the year and I think that's really important.
"I wanted to announce this early in the year so it wasn't a distraction for myself or anyone else. Now I can just put that aside and really focus on what we want to achieve this year as a team, which for me is the number-one priority."
Exeter head coach Rob Baxter revealed Dennis had been strongly recommended by former Chiefs skipper Dean Mumm.
"There are lots of similarities with Dean, positional-wise they can both play lock or in the back-row," added Baxter.
"They've both come from the Waratahs and, as I said, I've spoken to Dave, spoken to Dean, and they would have spoken themselves, and for me it's a comfortable and very good fit."
Dennis told Exeter's website: "Dean was a great sales rep for you guys. Speaking to him he had nothing but positive things to say about the Chiefs and his time over in England.
"He told me a lot of about the history of the club and the direction the Chiefs were heading in. He also mentioned about how the club had a great academy system and how they had brought through a lot of the guys who are now starting regularly each week. I think that's important in any club to have local guys coming through and it's something we have done at the Waratahs."