The City fan favourite and Premier League winner announced his decision after losing a lengthy battle with an injured knee.
His football journey, that took him from Oldham to City, abroad to Italy and back to Aston Villa, ends at the age of 31.
He will now concentrate on his business interests and will be back working with the Premier League champions in an ad hoc off-the-field role.
“Once a blue, always a blue,” he declared today with the trademark grin that made him so popular with peers and supporters alike.
“City has always been my spiritual home and where I enjoyed my best years as a player. Being part of the side that ended the long wait for silverware - in 2011 and 2012 - was very special. It kick-started this new era and the club has never looked back. What has happened since has been amazing.
“I feel lucky to have been asked back to help spread the City message and can’t wait to get going. I know it will be fun because City fans are incredible and always have been.”
Richards, who made his England debut in 2006 as an 18-year-old, hasn’t pulled on a football shirt in anger since 2016. A persistent knee problem just wouldn’t play ball and he admitted it has been hugely frustrating.
He was, however, at Wembley earlier this year to celebrate promotion with his Villa team-mates.
“I’m a footballer and I want to play football, but the knee would swell up to the point where I couldn’t even train properly,” he reflected. “I would have liked to have given Aston Villa more on the pitch, but it just wasn’t to be.
“Villa is a fantastic club, a very big club in all senses of the word and a great source of pride to the supporters. They looked after me very well and I have nothing but positive words to say about boss Dean Smith who was very positive and inclusive.
“It was great to be back at Wembley for the play-off final and celebrate with the team. It didn’t look great at one point earlier in the campaign, but everyone came together to produce the best end possible to the season. I wish everyone all the best for the return to the Premier League.”
The Leeds-raised Richards joined City at 14-years-old. Spotted playing for Oldham, he elected to join the then Platt Lane revolution because of City’s reputation for nurturing raw talent.
His power and physique meant he stood out among his intake from an early age and despite being the heart and soul of the 2005/06 Under-18 team seemingly headed for FA Youth Cup glory but, pipped at the post, he was fast-tracked into the first team by former manager Stuart Pearce.
Richards made his first-team debut at Highbury as a substitute during a 1-0 defeat to Arsenal – the team he supported as a kid - in October 2005.
Aged just 17, he was one of the youngest debutants in the club’s history and later that season he scored his first goal, a dramatic last-second header, ironically against Aston Villa, in an FA Cup fifth-round tie in the Midlands.
The unscripted, unfettered post-match interview that followed was the stuff of legend, landing him in hot-water and garnering affection in equal measure.
Richards never looked back at City. His debut for England Under-21s came against Moldova In August 2006, and a full England cap came in a 1-1 draw with Holland not long after, when at just 18-years-old, he became the youngest defender to represent the Three Lions, taking that record off cross-town rival Rio Ferdinand.
Injuries and the form of Pablo Zabaleta eventually meant Richards spent a year on loan at Fiorentina in Italy’s Serie A and he moved to Aston Villa in June 2015 after nearly 250 appearances in a City shirt.
Injury sidelined him for much of his stay in the Midlands and he managed only 31 starts in the past four seasons.
“It’s not the ideal way to finish a career for sure,” concluded the defender. “I’d much rather have said goodbye in the way Vinny (Kompany) did in his last few games for City but it wasn’t to be.
“It has been an unequal battle with injury ever since I left City and – being honest - for a good while during my last season at the Etihad.
“I finish my playing days happy that I reached the level that I did. I won the Premier League and the FA Cup, played for England and represented Great Britain at an Olympic games. I consider myself blessed and I am looking forward to renewing my many friendships at City. It is a special place that looks after its own.
“Whether I eventually take coaching badges and stay on that side of the game may be a decision for another time.”
City fans will get the chance to see Micah one more time in sky blue on the pitch when he returns to the Etihad in September for Vincent Kompany’s testimonial.