Dirksen commented: "I'm very happy. The Ospreys are the best team in Wales and I'm really happy to be a part of the organisation. I feel at home here, everybody has made very welcome and this is my region so I'm happy that I can continue playing for the Ospreys.
"I've been given some chances this season and I think I've taken them the best I can. It's great to be playing and training with top class players, Wales internationals and Lions, it's been an absolutely amazing year for me. It's nice to be in a squad with so many top class players that I can learn off.
"I'm really excited about the way the team is developing, we seem to be growing every day, every week. It's good to be finishing off the season with a final, we have worked hard to get there and now we have to make sure we don't let anybody down."
Head Coach, Steve Tandy, added: "Hanno has enjoyed a great season and has really shown what a talent he is. It's great that we can call on his services for another two seasons. If he continues to work hard and shows the attitude and desire to improve his all round game that we've seen from him since he joined the group, he could have a very bright future with the Ospreys."
Hailing from Krugersdorp in the Gauteng province of South Africa, he moved to the USA with his family in 2006 while still a teenager. Having represented the USA at age grade level, Dirksen became the youngest player to represent the Eagles at senior level when he featured in the non-capped match against Munster in Connecticut in August 2008.
He arrived in the UK to study at Truro College on a scholarship for the 2008/09 academic year before transferring his studies to Neath Port Talbot College in September 2009. He signed for Swansea shortly after, ending the campaign as top try-scorer as he touched down 21 times in just 22 games, claiming the Young Player of the Year award and putting pen to paper on a regional contract in January 2011.