Delaney is remaining at Emerald Headingley in an off-field role with the Leeds Rhinos Foundation.
The 32-year-old Australian, who made his Rhinos debut in 2010, will make a farewell appearance in the Boxing Day challenge game against Wakefield Trinity at Emerald Headingley.
Delaney, whose contract expires this autumn, has been dogged by injuries in recent seasons and is currently recovering from a fractured eye socket.
He plans to continue as a part-time player, but has yet to sign for another club.
He said: “When I left Australia I was a 24-year-old kid and I could never have imagined I would be privileged enough to play nine amazing seasons with a great club like Leeds.
“I would like to thank [chief executive] Gary Hetherington and [chairman] Paul Caddick for believing in me and giving me a chance to play for the Rhinos.
“I owe a debt of thanks to [former coach] Brian McDermott for everything he did for my career and likewise the great players I played alongside like Kevin Sinfield, Jamie Peacock, Kylie Leuluai, Rob Burrow, Danny McGuire and of course my old mate Ryan Bailey.
“I have run my blood to water week in and week out for the Rhinos and I wouldn’t change a thing.
“I understand the club need to move forward, especially as an overseas player and hopefully this will allow them to do that and bring in fresh blood as well as giving the great young kids at this club the chance to succeed and write their own names in the club’s history. I am sure they will.”
Delaney stressed: “I would like to thank the Rhinos fans for the incredible support they have given me over the years.
“The way I have been made to feel welcome in their city has been life changing for me. I am pleased I will get to say goodbye on the field on Boxing Day and pull on the Rhinos shirt one last time.
“It will special and I am looking forward to being back out there.”
Delaney has previously volunteered with the Rhinos’ foundation’s Onside Project, working with offenders in HMP Leeds and HMP Wealstun.
He said: “I am looking forward to working with Leeds Rhinos Foundation.
“I have enjoyed being able to give something back. I can relate to the programme having grown up in a tough environment.
“I have been able to show that you can choose a different pathway. Even if you get into trouble, that doesn’t mean your life is set on that course and you can still make something of your life.”
Rhinos director of rugby Kevin Sinfield paid tribute to Delaney.
“As a team mate Brett Delaney was a guy you always wanted beside you in the toughest of circumstances,” he said.
“His commitment and will to win was an inspiration to those around him. He was a regular NRL player when he arrived in 2010 and the fact he has spent his entire career with us shows his loyalty to the Rhinos cause down the years.
“It is great he will remain involved with Leeds Rhinos Foundation and he will always remain a Rhino.”
Bob Bowman, Leeds Rhinos Foundation’s chief operating officer, said: “We are delighted to welcome Brett on board.
“He has always supported the work of the foundation throughout his time at the club. He has impressed us with his ability to work with some of the most vulnerable and challenging members of our community and successfully influence those people to make positive lifestyle choices.”