O'Callaghan is in line to join English Premiership side Worcester Warriors on a two-year contract.
In becoming Munster's most capped player in February 2014 against Zebre (241 appearances) the former Highfield, CBC and Cork Con lock has gone on to represent the province on 268 occasions over 17 seasons.
The 36-year-old commenced the 2015/16 season by featuring in all three of Munster's pre-season games with his last appearance taking place on home soil in Cork last Friday night against London Irish where he was supported by his wife Jenny and family.
Fittingly the Cork-native made his Munster debut at the same venue when lining out against Edinburgh Reivers in August 1998 at 19 years of age. Two months later he made his European debut against Perpignan at Stade Aime Giral.
In his time with the province he was won two Heineken Cups, in 2006 and 2008, a Celtic League and 2 Magners League titles in 2003, 2009 and 2011 respectively, and a Celtic Cup in 2005.
On the International front O'Callaghan first tasted success at U19 level when winning the World Championship in 1998. He went on to make his senior debut against Wales in March 2003 and has made 94 appearances for his country.
Over an eleven year period he played his role in Ireland's three Triple Crown successes and played every minute of Ireland's Grand Slam winning campaign in 2009. In playing at every level he has featured in three World Cups, represented the Lions on two series (2005 and 2009), captaining the side to victory over the Southern Kings in Port Elizabeth in 2009, and represented the Barbarians in June 2014.
Commenting on his departure Donncha O'Callaghan said, "It has been a huge decision for me to leave Munster, one that I have thought long and hard about. The opportunity to prolong my career is one that I couldn't pass up and I'm extremely grateful to Munster, the IRFU and Worcester for providing me with this opportunity.
"Playing for both my home province and country has been a dream come true for me and my family, I have loved every moment of it. I leave with a full heart and unbelievable memories.
"I'm forever grateful to those in Munster and Irish Rugby that put the structures in place all the way up, and most importantly, the people that have influenced and shaped me not only as a player but as a person.
"My goal is the same now as it was when I was 8 years of age, to play rugby, enjoy it and win. I look forward to earning the respect of the Worcester management, players and supporters.
"Finally I would like to thank the Munster supporters - for over 17 years you have lifted me to play beyond myself and I look forward to going back and joining you in my first role with Munster, as a supporter."
Commenting on the news Munster Rugby CEO Garrett Fitzgerald said, "I have known Donncha since his schooldays with CBC. Throughout his rugby career he has been the consummate professional and a leader in his field, raising the bar in every squad he was associated with through his attitude, work ethic and discipline.
"A proud Cork, Munster and Irish man he has forged the way for up-and-coming players always leading by example and setting the highest standards on and off the pitch.
"We say farewell and thanks to a man that gave everything to the red jersey for seventeen years, and wish him all the best for the future."
Head Coach Anthony Foley said, "I had the honour of playing with Donncha for over a decade and have witnessed first-hand everything he has achieved with Munster and Ireland.
"A true Munster man in every sense, his passion and commitment were clear for all to see. He is held in the highest regard on the world stage after excelling at every level and we are thankful for his immense contribution to the province."
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