The highly-rated 24-year-old joins the Welsh region having spent the last two seasons in Japan.
Before his move to Yokohama in Japanese top division, 6ft 7in Douglas, who has played in the second row and back row, featured for the Waratahs in Super Rugby and the Manly club in Sydney.
Douglas is Scarlets’ fourth signing announced for the 2024-25 campaign, with Exeter prop Alec Hepburn, Cheetahs hooker Marnus van der Merwe and Nottingham full-back Ellis Mee on their way to west Wales.
Tongan second row Sam Lousi, Wales internationals Tom Rogers and Harri O’Connor and back-rowers Dan Davis and Ben Williams have also signed new contracts with the club.
Speaking on his new signing Scarlets head coach Dwayne Peel said:
“Max is a young, athletic second row who has experience in Super Rugby and more recently in Japan’s top division.
“He is comfortable with the ball hand, which suits how we are looking to play and is excited about coming on board and being part of the Scarlets journey over the coming years.
“Max is another strong addition to our forward pack following the signings of Marnus van der Merwe and Alec Hepburn and we are looking forward to welcoming him here to Parc y Scarlets this summer.”
Delighted with his move Max Douglas said:
“I’m really excited to be joining the Scarlets. This is a club with a strong history and I’m excited at the challenge of trying to contribute to that.
“I’m looking to bring over some of the experiences and learnings I’ve gained from my time in Australia and Japan to hopefully add to what is a really strong playing group.
“I can’t wait to meet all the players and staff and get into our work.”
[Lead image: Scarlets Rugby]