He was also capped 128 times by Ireland and was a veteran of three British and Irish Lions tours but will be remembered by the Munstermen for guiding them to two Heineken Cup successes in 2006 and 2008.
However, O'Gara has revealed the lure of coaching has made the decision to step aside a lot easier.
"I have ambitions in the years ahead to coach at a high level and, with this in mind, I can confirm now that I will be joining Racing Metro's coaching staff in July," he told the Irish Examiner.
O'Gara's teammate with both Munster and Ireland Donncha O'Callaghan, though, claims he will be impossible to replace.
"To gauge the impact this (retirement) will have you have to understand the phenomenal type of character he is," said O'Callaghan.
"Every day he turns up for training, he brings a standard, sets that standard and never drops it an inch. And expects no less from anyone else no matter whether that's with Munster, Ireland, the Lions, makes no difference to him.
"There are so many players, and I include myself top of that list, who are so much better players for being around him."
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