The 24-year old wing has enjoyed 2 stints at the Dragons, with international call-ups resulting from both his periods at Rodney Parade.
'I'm looking forward to moving abroad but I also leave the Dragons with a heavy heart," he said.
"I had opportunities to join other teams in Wales and England but had no interest in playing for any other team in the UK.
"The Dragons have given me the opportunity to play Regional Rugby, they have helped me achieve my ambition of playing International Rugby and made me the player that I am today.
Following his fantastic form for the Dragons last season, Aled was part of Gatland's squad for the World Cup but felt frustrated after being left out of this season's Six Nations campaign. "Not being chosen for the Welsh 6 Nations squad has played a part in my decision to move abroad but I also feel that experience in a different league will make me a better player."
Brew has been a fan's favourite at Rodney Parade and a key part of the regional side, picking up his 100th appearance this weekend.
"The Dragons couldn't have done any more to keep me in Wales, they made me a fantastic offer to stay but I just feel the time is right for me and my young family to experience a new culture, way of life and also a new rugby experience.
"I would like to thank the Dragons board, Management team, players and especially the fantastic supporters for everything that they have done for me and I wish the team every success for the future."
Dragons' Director of Rugby Robert Beale said "We understand Aled's desire to take on a new challenge abroad. Players have relatively short careers and these decisions are often about much more than just rugby.
"Aled has been a great servant to the Dragons and he will be missed by the players, coaches and supporters alike.
"We are confident as a region that we are developing quality players and the likes of Matthew Pewtner and Lewis Robling, not to mention Hallam Amos and Jack Dixon show that there is a strong future Dragons rugby."
There will be no further comment from Aled or the Dragons regarding his future team at this stage.
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