Winger Joe Tomane will reunite with former mentor Jake White at Montpellier, with the Brumbies confirming the winger's impending departure on Tuesday.
Reports first emerged last November in French newspapers that Tomane was considering a move to the Top 14 but he initially rejected that speculation.
Tomane has penned a statement on the Brumbies website, thanking the Canberra community.
"I am writing this message to everybody who has supported myself and the Brumbies over my five seasons with the club, as a heartfelt way to say thank you for everything you have done in my time with this great team," the statement read.
The 26-year-old said he hoped to return to Australia in the future, to add to his Test caps.
"I have given my all to Australian Rugby and have been lucky enough to represent the Wallabies at the Rugby World Cup, which is every young player's dream growing up," the statement read.
"I hope that the possibility of returning to the Wallabies in the future is something that could happen, however right now my focus is doing everything I can to help the Brumbies in 2016 before my move to France."
Tomane said his focus would be entirely on returning from injury to feature for the brumbies as they vie for the Super Rugby title.
"I’m excited by the opportunity this current group has over the remaining matches we have in 2016 and truly believe we can win this year’s Super Rugby title," he said.
"This news just gives me even more drive to repay the faith of the Brumbies and the support of our fans."
Brumbies coach Stephen Larkham said the club was disappointed to see Tomane leave but the team had little choice in the matter.
“Joe was having a great year before he injured his knee,” he said in a statement.
“He was definitely in the mix for Wallabies selection for the England series before the injury, which is unfortunate because I know how much it means to him to represent his country.
“Whilst we are disappointed he will be leaving the club, there are limitations to what we are currently able to do if players garner overseas interest. In the end he felt this was his best option regarding his career and his family.”
Montpellier will have a star-studded wing department next season, with Crusaders and Fiji star Nemani Nadolo also headed to the French club after this Super Rugby season.
Nadolo has had a French stint in the past, playing for Bourgoin from 2010-11.
Tomane is the latest in a string of players who won't feature for the Brumbies in the 2017 season, with Matt Toomua (Leicester), Stephen Moore ( Queensland) and David Pocock (2017 sabbatical) all moving away from Canberra next season.
Co-captain Christian Lealiifano spurned the possibility of an overseas stint by re-signing with the Canberra club earlier this season.