- Macarthur FC (Football)
- Maccabi Haifa (Football)
- Maccabi Haifa (Basketball)
- Maccabi Netanya (Football)
- Maccabi Petah Tikva (Football)
- Maccabi Ra'anana (Basketball)
- Maccabi Tel Aviv (Football)
- Maccabi Tel Aviv Basketball Club (Basketball)
- Macclesfield Town (Football)
- Maciej Sulecki (Boxing)
- Madagascar (Football)
- Madagascar (Rugby Union)
- Madagascar Women (Rugby Union)
- Madhya Pradesh (Cricket)
- Madhya Pradesh Under-16s (Cricket)
- Madhya Pradesh Women (Cricket)
- Magomed Kurbanov (Boxing)
- Magpies (Netball)
- Magpies Crusaders FC (Football)
- Maharashtra (Cricket)
- Maharashtra Women (Cricket)
- Mahe Megalo Strikers (Cricket)
- Mahmudullah XI (Cricket)
- Maidenhead United (Football)
- Maidenhead United Women (Football)
- Maidstone Utd (Football)
- Maine (American Football)
- Maine (Basketball)
- Mainland Tactix (Netball)
- Mainz (Football)
- Mairis Briedis (Boxing)
- Maitland (Football)
- Makedonija GP (Football)
- Malawi (Netball)
- Malawi (Football)
- Malawi Women (Cricket)
- Malaysia (Football)
- Malaysia (Cricket)
- Malaysia (Hockey)
- Malaysia Club XI (Cricket)
- Malaysia Women (Cricket)
- Malaysia Women Under-19s (Cricket)
- Maldives (Cricket)
- Maldives Women (Cricket)
- Maldon (Football)
- Mali (Football)
- Mali Women (Basketball)
- Malmo FF (Football)
- Malta (Football)
- Malta (Rugby League)
- Malta U21 (Football)
- Malta Women (Football)
- Malta Women (Cricket)
- Mamelodi Sundowns (Football)
- Manawatu (Rugby Union)
- Manawatū (Rugby Union)
- Manawatū Cyclones (Rugby Union)
- Manchester Basketball (Basketball)
- Manchester Basketball Women (Basketball)
- Manchester City (Football)
- Manchester City U21 (Football)
- Manchester City Women (Football)
- Manchester Giants (Basketball)
- Manchester Originals (Cricket)
- Manchester Storm (Ice Hockey)
- Manchester Thunder (Netball)
- Manchester United (Football)
- Manchester United U21 (Football)
- Manchester United Women (Football)
- Mancunian Unity Women (Football)
- Mangalore Dragons (Cricket)
- Mangalore United (Cricket)
- Manipal Tigers (Cricket)
- Manipur (Cricket)
- Manipur Women (Cricket)
- Manly United (Football)
- Manny Pacquiao (Boxing)
- Mansfield Town (Football)
- Manuel Gallegos (Boxing)
- Māori All Blacks (Rugby Union)
- Maratha Arabians (Cricket)
- Marcelo Coceres (Boxing)
- Marco Antonio Barrera (Boxing)
- Marconi Stallions FC (Football)
- Marcus Browne (Boxing)
- Mardan Warriors (Cricket)
- Maria Ines Ferreyra (Boxing)
- Maribor (Football)
- Marie Eve Dicaire (Boxing)
- Marine (Football)
- Marine Academy Plymouth Ladies (Football)
- Mario Abel Cazares (Boxing)
- Mario Barrios (Boxing)
- Marist (Basketball)
- Marítimo M. (Football)
- Mariusz Wach (Boxing)
- Mark DeLuca (Boxing)
- Mark Heffron (Boxing)
- Mark Magsayo (Boxing)
- Markhors (Cricket)
- Marko Calic (Boxing)
- Marko Nikolic (Boxing)
- Marlon Moraes (Mixed Martial Arts)
- Marlon Tapales (Boxing)
- Marquette (Basketball)
- Marsaxlokk (Football)
- Marseille (Football)
- Marshall (American Football)
- Marshall (Basketball)
- Martin Bakole (Boxing)
- Martin Murray (Boxing)
- Martinique (Football)
- Marwari College Women (Cricket)
- Maryland (Basketball)
- Maryland (American Football)
- Marylebone Cricket Club Women (Cricket)
- Masanori Rikiishi (Boxing)
- Masayoshi Nakatani (Boxing)
- Masayuki Ito (Boxing)
- Mashonaland Eagles (Cricket)
- Massachusetts (American Football)
- Matabeleland Tuskers (Cricket)
- Mateusz Masternak (Boxing)
- Mathieu Germain (Boxing)
- Maurice Hooker (Boxing)
- Mauricio Lara (Boxing)
- Mauritania (Football)
- Mauritius (Football)
- Mavericks (Netball)
- Max Holloway (Mixed Martial Arts)
- Maxi Hughes (Boxing)
- Maxim Vlasov (Boxing)
- Mayo (Hurling)
- Mayo (Gaelic Football)
- Mazatlán F.C. (Football)
- McNeese (American Football)
- McNeese State (Basketball)
- McWilliams Arroyo (Boxing)
- Mea Motu (Boxing)
- Meath (Hurling)
- Meath (Gaelic Football)
- Meghalaya (Cricket)
- Meghalaya Women (Cricket)
- Meizhou Hakka (Football)
- Melbourne (Australian Rules Football)
- Melbourne City FC (Football)
- Melbourne Ducks (Ice Hockey)
- Melbourne Ice Women (Ice Hockey)
- Melbourne Knights (Football)
- Melbourne Renegades (Cricket)
- Melbourne Renegades Women (Cricket)
- Melbourne Stars (Cricket)
- Melbourne Stars Women (Cricket)
- Melbourne United (Basketball)
- Melbourne Victory (Football)
- Melissa St Vil (Boxing)
- Melvin Lopez (Boxing)
- Memphis (American Football)
- Memphis (Basketball)
- Memphis Grizzlies (Basketball)
- Memphis Showboats (American Football)
- Mercer (American Football)
- Mercer (Basketball)
- Mercito Gesta (Boxing)
- Merrimack (American Football)
- Merseyrail Ladies (Football)
- Merthyr Town (Football)
- Metropolitan Riveters (Ice Hockey)
- Metz (Football)
- Mexico (Football)
- Mexico (Tennis)
- Mexico (Volleyball)
- Mexico (Baseball)
- Mexico (Basketball)
- Mexico Women (Lacrosse)
- MFK Karviná (Football)
- MFK Ruzomberok (Football)
- MI Cape Town (Cricket)
- MI Emirates (Cricket)
- MI New York (Cricket)
- Miami (Basketball)
- Miami (FL) (American Football)
- Miami (OH) (American Football)
- Miami Dolphins (American Football)
- Miami Heat (Basketball)
- Miami Lions (Cricket)
- Miami Marlins (Baseball)
- Miami Sharks (Rugby Union)
- Michael Conlan (Boxing)
- Michael Dasmarinas (Boxing)
- Michael Hunter (Boxing)
- Michael McKinson (Boxing)
- Michael Seals (Boxing)
- Michael Wallisch (Boxing)
- Michael Williams Jr (Boxing)
- Michal Cieslak (Boxing)
- Michigan (Basketball)
- Michigan (American Football)
- Michigan Panthers (American Football)
- Michigan State (Basketball)
- Michigan State (American Football)
- Mid West Rhinos (Cricket)
- Middle Tennessee (American Football)
- Middle Tennessee (Basketball)
- Middlesbrough (Football)
- Middlesbrough Ladies (Football)
- Middlesex (Cricket)
- Middlesex 2nd XI (Cricket)
- Middlesex Women (Cricket)
- Miguel Berchelt (Boxing)
- Miguel Flores (Boxing)
- Miguel Marriaga (Boxing)
- Miguel Vazquez (Boxing)
- Mikael Zewski (Boxing)
- Mikaela Mayer (Boxing)
- Mike Dallas Jr (Boxing)
- Mike Perry (Boxing)
- Mike Tyson (Boxing)
- Mikey Garcia (Boxing)
- Mikkel LesPierre (Boxing)
- Mikuru Asakura (Boxing)
- Millonarios (Football)
- Millwall (Football)
- Millwall Lionesses (Football)
- Millwall Lionesses Ladies (Football)
- Milton Keynes Dons (Football)
- Milwaukee Brewers (Baseball)
- Milwaukee Bucks (Basketball)
- Minister Rajshahi (Cricket)
- Minnesota (Basketball)
- Minnesota (American Football)
- Minnesota (Ice Hockey)
- Minnesota Frost (Ice Hockey)
- Minnesota Golden Gophers (Baseball)
- Minnesota Lynx (Basketball)
- Minnesota Timberwolves (Basketball)
- Minnesota Twins (Baseball)
- Minnesota United FC (Football)
- Minnesota Vikings (American Football)
- Minnesota Whitecaps (Ice Hockey)
- Minnesota Wild (Ice Hockey)
- Minsterhaka (Cricket)
- Miriam Gutierrez (Boxing)
- Mirpur Royals (Cricket)
- Mississippi State (American Football)
- Mississippi State (Basketball)
- Missouri (American Football)
- Missouri (Basketball)
- Missouri State (American Football)
- Missouri State (Basketball)
- Mizoram (Cricket)
- Mizoram Women (Cricket)
- Mjällby AIF (Football)
- Mjøndalen (Football)
- MK Dons Ladies (Football)
- MLS All-Stars (Football)
- Moana Pasifika (Rugby Union)
- Modbury Jets (Football)
- Mohammedan Sporting Club (Cricket)
- Molde (Football)
- Moldova (Football)
- Moldova U21 (Football)
- Moldova Women (Football)
- Monaco (Football)
- Monaco (Tennis)
- Monaghan (Hurling)
- Monaghan (Gaelic Football)
- Moneyfields Women (Football)
- Mongolia (Football)
- Mongolia (Cricket)
- Mongolia Women (Cricket)
- Monmouth (American Football)
- Monmouth (Basketball)
- Montana (American Football)
- Montana Love (Boxing)
- Montana State (American Football)
- Montana State (Basketball)
- Montenegro (Football)
- Montenegro (Basketball)
- Montenegro (Handball)
- Montenegro U19 (Football)
- Montenegro U21 (Football)
- Montenegro Women (Football)
- Montenegro Women (Basketball)
- Monterrey (Football)
- Monterrey Femenil (Football)
- Montpellier (Football)
- Montpellier (Rugby Union)
- Montreal (Ice Hockey)
- Montreal Alouettes (Canadian Football)
- Montreal Canadiens (Ice Hockey)
- Montreal Force (Ice Hockey)
- Montreal Roses FC (Football)
- Montreal Tigers (Cricket)
- Montréal Victoire (Ice Hockey)
- Montrose (Football)
- Montrose Women (Football)
- Montserrat (Football)
- Monza (Football)
- Moors Sports Club (Cricket)
- Morecambe (Football)
- Morehead State (Basketball)
- Moreirense FC (Football)
- Moreland Zebras (Football)
- Moreton City Excelsior (Football)
- Morgan State (American Football)
- Morningside (Australian Rules Football)
- Morocco (Football)
- Morocco (Tennis)
- Morocco (Handball)
- Morocco Women (Football)
- Morrisville Samp Army (Cricket)
- Morrisville Unity (Cricket)
- Morton (Football)
- Moruti Mthalane (Boxing)
- Motherwell (Football)
- Motherwell Women (Football)
- Mount Druitt Town Rangers (Football)
- Mount St. Mary's (Basketball)
- Mountaineers (Cricket)
- Mountaineers Women (Cricket)
- Mozambique (Football)
- Mozambique (Cricket)
- Mozambique Women (Cricket)
- Mpumalanga (Cricket)
- Mpumalanga Women (Cricket)
- MSK Zilina (Football)
- Mt Gravatt (Australian Rules Football)
- Muhammad Waseem (Boxing)
- Mulbarton Wanderers Women (Football)
- Multan Region (Cricket)
- Multan Sultans (Cricket)
- Mumbai (Cricket)
- Mumbai Indians (Cricket)
- Mumbai Indians Women (Cricket)
- Mumbai Women (Cricket)
- Munster Reds (Cricket)
- Munster Rugby (Rugby Union)
- Murat Gassiev (Boxing)
- Murray State (Basketball)
- Murray State (American Football)
- Musselburgh Athletic (Football)
- Muzzaffarabad Tigers (Cricket)
- Myanmar (Football)
- Myanmar (Cricket)
- Myanmar Women (Cricket)
- Mysuru Warriors (Cricket)