| Magika Pallacanestro | — | Castel San Pietro Terme | — | — |
| Magnolia Basket Campobasso | — | Campobasso | 2017 | — |
| Mariscal Miller | Copa Perú | — | — | Estadio Jorge Basadre |
| Mariscal Nieto de Ilo | Copa Perú | — | — | Estadio Mariscal Nieto |
| Mariscal Sucre | — | — | 1925 | Stadio nazionale del Perù |
| Maurolico Messina | — | — | — | — |
| Maxima Roma | Serie A | — | 2026 | Palazzo dello Sport |
| Memphis Grizzlies | National Basketball Association | Memphis | 1995 | Pyramid Arena, FedExForum |
| Meyana Mesagne | — | Mesagne | — | — |
| Miami Dolphins | National Football League | Miami | 1966 | Hard Rock Stadium |
| Miami Heat | National Basketball Association | Miami | 1988 | Miami Arena, Kaseya Center |
| Miami Marlins | Major League Baseball | — | 1993 | LoanDepot Park, Hard Rock Stadium |
| Miguel Grau de Abancay | Copa Perú | — | 1955 | Estadio Monumental de Condebamba |
| Milwaukee Braves | Major League Baseball | Milwaukee | 1953 | Milwaukee County Stadium |
| Milwaukee Brewers | Major League Baseball | Milwaukee | 1969 | American Family Field |
| Milwaukee Bucks | National Basketball Association | Milwaukee | 1968 | UW–Milwaukee Panther Arena, BMO Harris Bradley Center, Fiserv Forum |
| Mina San Vicente | Copa Perú | — | giugno 1970 | — |
| Minnesota North Stars | — | Bloomington | 1967 | Met Center |
| Minnesota Timberwolves | National Basketball Association | Minneapolis | 1989 | Hubert H. Humphrey Metrodome, Target Center |
| Minnesota Twins | Major League Baseball | — | 1901 | Target Field, American League Park, Metropolitan Stadium, Hubert H. Humphrey Metrodome, Boundary Field, Griffith Stadium |
| Minnesota United FC | Major League Soccer | Minneapolis | 2015 | Allianz Field, TCF Bank Stadium |
| Minnesota Vikings | National Football League | Minnesota | 1961 | Metropolitan Stadium, TCF Bank Stadium, Hubert H. Humphrey Metrodome, U.S. Bank Stadium |
| Minnesota Wild | — | Saint Paul | 2000 | Xcel Energy Center |
| Miraflores Foot-Ball Club | Copa Perú | — | 29 maggio 1922 | Stadio nazionale del Perù |
| Miraflores Sporting Club | — | — | — | Estadio Nacional del Perú |
| Modena Basket | — | — | — | — |
| Moncalieri Basketball | — | Moncalieri | — | — |
| Montigarda Basket | — | Montichiari | — | — |
| Montreal Maroons | — | — | 1924 | Forum de Montréal |
| MTVB Herons Basket | — | Montecatini Terme | — | — |