His appointment will see him reunited with Scott Johnson and Andrew Hore, who were also part of the coaching team in 2005. Since May 2008, his WRU responsibilities have seen him spending time working during non-international times with Welsh players at both the Ospreys and the Scarlets.
A former flanker for Swansea and Cardiff, he was capped at every level from schoolboy up as a player. He gained three senior caps in 1995, making his debut against New Zealand in the Rugby World Cup in South Africa. After finishing his playing career with Bristol, he moved in to role of Conditioning Coach at the then English top-flight club.
Andrew Hore, Ospreys Elite Performance Director, commented: "The addition of Mark Bennett to our coaching team at the Ospreys is an exciting appointment and represents a major coup for the region. He has a proven track record, working both in the Guinness Premiership with Bristol and more recently, in the international scene where he has been a key part of the WRU conditioning team for the last five years years, helping Wales to achieve two Grand Slams during this time.
"He has outstanding theoretical knowledge and is a world leader in the field of strength development. Importantly, he possesses the skills and ability to be able to apply it in the field. The best thing about this appointment, is that Mark is already a familiar face in the camp through his WRU role and will already know intimately the vast majority of the squad, their fitness, habits and personalities, allowing him to hit the ground running when he arrives in pre-season.
Being a local boy who originally comes from Ospreylia, it is particularly pleasing that we are able to bring a world class talent back to his home region."
Current Wales head coach Robin McBryde said: "Mark goes to the Ospreys with the blessings of everyone at Wales HQ, he has been a tremendous servant to the national game since he first joined the WRU in 2004 and in my own time as a national coach I have seen first hand, not just the hard work he puts into his job, but the very real and tangible results that he produces in the players he works with.
"What is particularly satisfying about this appointment is that Mark's talents are to be retained by Welsh rugby and the national team will continue to benefit from the fitness and conditioning standards he sets.
"We can be confident that international players of the future coming from the Ospreys region will continue to be in the very best condition with Mark at the helm and we wish him well in his continued career at the top level of elite sport."