The 48-year-old Dane, who won five Premier League titles, three FA Cups and the Champions League during a trophy-laden eight-year spell at Old Trafford, will join the likes of Sir Bobby Charlton, Bryan Robson, Gary Neville and Andrew Cole in helping to promote the Red Devils.
Schmeichel told the club's official website, www.manutd.com: "It's a great honour to be an ambassador for Manchester United.
"I spent many happy years at the club and achieved some of my greatest sporting accolades whilst playing here, so I was delighted to be asked to take up this role.
"I am looking forward to working with United again and sharing my experiences, as well as catching up with some of my former team-mates."
Schmeichel, who won 129 caps for Denmark, became a massive crowd favourite during his playing career with United and skippered the Red Devils to their famous 1999 Champions League win over Bayern Munich, when Roy Keane was suspended.