Welsh great Phillips to retire
The 34-year-old scrumhalf – capped 94 times by his country – said he will bow out at the conclusion of English Premiership side Sale Sharks' season, which has three matches remaining.
"I would like to announce my retirement as a professional rugby player at the end of this season with @SaleSharksRugby," Phillips wrote on Twitter.
"Thanks to the fans, teammates, club, coaches, @WelshRugbyUnion the @LionsOfficial, friends & family who have supported me over the years.
"I will attack the next chapters with the same passion, commitment and laughter as I did with my entire career. See you soon!"
Sale's Rugby Director Steve Diamond paid a handsome tribute to Phillips.
"On behalf of the club and the rest of the coaches, I would like to thank Mike for his massive contribution this season to the squad," said Diamond.
"He's a great lad and a true professional, and we as a club have learnt a lot from him."
Phillips was an integral part of two Six Nations Grand Slam-winning sides and went to three World Cups in addition to representing the British and Irish Lions in five Tests.
The Welshman, who is heavily involved in charity work with children, played club rugby in three countries, lining up for the likes of Cardiff Blues, French outfits Bayonne and Racing 92, and then Sale.
However, he was also involved in several alcohol-related incidents during his career which resulted in disciplinary action, including being sacked by Bayonne in 2013.
Phillips joined Sale at the start of this season, although the Sharks are 10th in the Premiership and out of contention for a place in the title play-offs.
Phillips, who retired from Test rugby at the end of 2015, also received many good wishes from former teammates and opponents alike such as former Ireland and Lions star Stephen Ferris.
"Best of luck big man. Legend," tweeted Ferris.