| Island’s Name | Island group(s) | Country/Countries |
| Ma Wan | Hong Kong | China |
| Maadhiguvaru | Gaafu Alif Atoll | Maldives |
| Machias Seal | Disputed Between Maine and New Brunswick | Disputed between United States and Canada |
| Mackay | North Carolina and Virginia | United States |
| Mackenzie King | Queen Elizabeth Islands, Nunavut and Northwest Territories | Canada |
| Mackinac | Lake Huron, Michigan | United States |
| Maclellan | Tennessee River, Tennessee | United States |
| Macquarie | Southern Ocean, Tasmania | Australia |
| Madagascar | Indian Ocean | Madagascar |
| La Maddalena | Sardinia | Italy |
| Iles des Madeleines | | Senegal |
| Madeline | Lake Superior, Wisconsin | United States |
| Madeira | Madeira | Portugal |
| Madrid Bar | Mississippi River, Kentucky | United States |
| Madura | East Java | Indonesia |
| Maewo | Pacific Ocean | Vanuatu |
| Mafia | Tanzanian Spice Islands | Tanzania |
| Isla Magdalena | Baja California Sur | Mexico |
| Magerøya | Nordkapp, Finnmark | Norway |
| Mageshima | Osumi Islands part of the Satsunan Islands group of the Ryukyu Islands | Japan |
| Magusaiai | Shortland Islands | Solomon Islands |
| Maiao | Windward Islands, Society Islands, French Polynesia | Overseas Lands of France |
| Mainau | Lake Constance | Germany |
| Mainland | Shetland Islands | Scotland |
| Main Station | Lake Huron, Ontario | Canada |
| Majorca | Balearic Islands | Spain |
| Majuli | Brahmaputra River, Assam | India |
| Majuro | Ratak Chain | Marshall Islands |
| Makada | Duke of York Islands | Papua New Guinea |
| Makanrushi | Kuril Islands, Sakhalin Oblast | Russia |
| Makatea | Tuamotus, French Polynesia | France |
| Makema | Tuamotus, French Polynesia | France |
| Makura | Shepherd Islands | Vanuatu |
| Malakula | New Hebrides | Vanuatu |
| Malcolm | British Columbia | Canada |
| Malden | Line Islands | Kiribati |
| Mal Grad | Lake Prespa | Albania |
| Mallard | Lake Audubon, North Dakota | United States |
| Malo | Pacific Ocean | Vanuatu |
| Maloelap Atoll | Ratak Chain | Marshall Islands |
| Malpelo | | Colombia |
| Malta | Maltese islands | Malta |
| Makronisos | | Greece |
| Mamula | Adriatic Sea | Montenegro |
| Man | Ontario | Canada |
| Mana | Porirua Harbour | New Zealand |
| Manda | Lamu Archipelago | Kenya |
| Mandø | North Frisian Islands | Germany |
| Mangaia | Cook Islands | Cook Islands |
| Manhattan | New York | United States |
| Manihi | King George Islands, Tuamotus, French Polynesia | France |
| Manihiki | Cook Islands | Cook Islands |
| Manilaid | Gulf of Riga | Estonia |
| Manitou | Lake Superior, Michigan | United States |
| Manitou | Apostle Islands, Wisconsin | United States |
| Manitoulin | Lake Huron, Ontario | Canada |
| Manoel | Maltese islands | Malta |
| Mansel | Nunavut | Canada |
| Manuae | Cook Islands | Cook Islands |
| Manuae | Leeward Islands, Society Islands, French Polynesia | French Polynesia |
| Manus | Admiralty Islands | Papua New Guinea |
| Maple | Mississippi River, Missouri | United States |
| Ilha de Marajó | | Brazil |
| Marawah, United Arab Emirates | Persian Gulf | United Arab Emirates |
| Mare | California | United States |
| Marechal | Beira Baixa islands | Portugal |
| Marettimo | Aegadian Islands | Italy |
| Isla Margarita | Nueva Esparta | Venezuela |
| Margitsziget | Danube River | Hungary |
| Maria | Tasmania | Australia |
| Maria Cleofas | Islas Marías, Nayarit | Mexico |
| Maria Madre | Islas Marías, Nayarit | Mexico |
| Maria Magdalena | Islas Marías, Nayarit | Mexico |
| Marie-Galante | Guadeloupe, Lesser Antilles | France |
| Marinduque | Luzon | Philippines |
| Marinha Nova | Beira Litoral islands | Portugal |
| Mark | Lake Winnipesaukee, New Hampshire | United States |
| Marmara | Marmara Islands | Turkey |
| Marrowstone | Puget Sound, Washington | United States |
| Marsh | Louisiana | United States |
| Marshall | Maine | United States |
| Martha's Vineyard | Massachusetts | United States |
| Martin | Louisiana | United States |
| Ilhas Martin Vaz | Atlantic Ocean | Brazil |
| Martinhal | Algarve islands | Portugal |
| Martuska-sziget | Danube River | Hungary |
| Maskali | | Djibouti |
| Masnedø | | Denmark |
| Mason | Mississippi River, Missouri | United States |
| Mason's | Mystic River, Connecticut | United States |
| Massey | Queen Elizabeth Islands, Nunavut | Canada |
| Matadouce | Beira Litoral islands | Portugal |
| Matagorda | Texas | United States |
| Mataiva | Palliser Islands, Tuamotus, French Polynesia | France |
| Matakana | Bay of Plenty | New Zealand |
| Mataso | Shepherd Islands | Vanuatu |
| Mathraki | Ionian Islands | Greece |
| Matia | San Juan Islands, Washington | United States |
| Matinicus | Maine | United States |
| Matiu | Wellington Harbour | New Zealand |
| Maatsukyer | Maatsuyker Island Group, Tasmania | Australia |
| Matsu | Lienchang County | Republic of China |
| Matty | Nunavut | Canada |
| Matua | Kuril Islands, Sakhalin Oblast | Russia |
| Matureivavao | Acteon Group, Tuamotus, French Polynesia | France |
| Maupiti | Windward Islands, Society Islands, French Polynesia | Overseas Lands of France |
| Maud | Marlborough Sounds | New Zealand |
| Maui | Hawaiian Islands, Hawaii | United States |
| Mauke | Cook Islands | Cook Islands |
| Mauritius | Mascarene Islands | Mauritius |
| Maurice Island | | Latvia |
| Maury | Puget Sound, Washington | United States |
| Mausinsel | Bavaria, Bavaria | Germany |
| Maxwell | Georgian Bay Ontario | Canada |
| Mayne | Gulf Islands, British Columbia | Canada |
| Mayor | Bay of Plenty | New Zealand |
| Mayotte | Comoros | France |
| Mazaki | | Cyprus |
| McCallum | Lake Huron, Ontario | Canada |
| McCauley | British Columbia | Canada |
| McCormicks | Susquehanna River, Pennsylvania | United States |
| McCoy | Georgian Bay Ontario | Canada |
| McCoy | Mississippi River, Illinois | United States |
| McEvers | Illinois River, Illinois | United States |
| McLaren | Georgian Bay Ontario | Canada |
| McNeil | Puget Sound, Washington | United States |
| McQuade | Georgian Bay Ontario | Canada |
| McQueens | Georgia | United States |
| Isle of Meadows | New York | United States |
| Medny | Komandorski Islands, Alaska | Owned by the United States, controlled by Russia |
| Meganisi | Ionian Islands | Greece |
| Mehetia | Windward Islands, Society Islands, French Polynesia | Overseas Lands of France |
| Meighen | Queen Elizabeth Islands, Nunavut | Canada |
| Mejit | Ratak chain | Marshall Islands |
| Melbourne | Nunavut | Canada |
| Mele | Melanesia | Vanuatu |
| Mellum | East Frisian Islands | Germany |
| Melville | Queen Elizabeth Islands, Nunavut and Northwest Territories | Canada |
| Melvin | Lake Winnipesaukee, New Hampshire | United States |
| Memmert | East Frisian Islands | Germany |
| Mendicant | Barataria Bay, Louisiana | United States |
| Merasheen | Newfoundland and Labrador | Canada |
| Mercer | Lake Washington, Washington | United States |
| Mercury | | New Zealand |
| Merelava | Banks Islands | Vanuatu |
| Merig | Banks Islands | Vanuatu |
| Metinic | Maine | United States |
| Metoma | Torres Islands | Vanuatu |
| Michigan | Lake Superior, Wisconsin | United States |
| Michipicoten | Lake Superior, Ontario | Canada |
| Middle Andaman | Andaman Islands | India |
| Middle Bass | Bass Islands, Ohio | United States |
| Middle Brewster | Boston Harbor, Massachusetts | United States |
| Middle Duck | Lake Huron, Ontario | Canada |
| Middle Ground | Mississippi River, Mississippi | United States |
| Middle Ground Coastal Battery | Maharashtra | India |
| Middle | Lake Erie, Ontario | Canada |
| Middle | Ohio River, West Virginia | United States |
| Middle | Nightingale Islands, Tristan da Cunha | British overseas territory of Saint Helena, Ascension and Tristan da Cunha |
| Midgarth | Orkney Islands | Scotland |
| Mikurajima | Izu Islands | Japan |
| Mile | Lake Winnipesaukee, New Hampshire | United States |
| Mili Atoll | Ratak Chain | Marshall Islands |
| Mill | Nunavut | Canada |
| Mill Creek | Ohio River, West Virginia | United States |
| Mill Rock | New York | United States |
| Milos | Cyclades | Greece |
| Mimami daitō | Daitō Islands part of the Ryukyu Islands | Japan |
| Minami Kojima | Senkaku Islands | Disputed by Japan and China |
| Mindanao | Mindanao group | Philippines |
| Minicoy | Lakshadweep | India |
| Minister | Lake Winnipesaukee, New Hampshire | United States |
| Mink | Georgian Bay Ontario | Canada |
| Mink | Lake Winnipesaukee, New Hampshire | United States |
| Minna | Miyako Islands part of the Sakishima Islands part of the Ryukyu Islands | Japan |
| Minnicognashene | Georgian Bay Ontario | Canada |
| Minorca | Balearic Islands | Spain |
| Minquiers | Channel Islands | Jersey |
| Minu | Persian Gulf | Iran |
| Mioko | Duke of York Islands | Papua New Guinea |
| Miserable | Rice Lake, Illinois | United States |
| Mishka | Danube River | Bulgaria |
| Miskan | Persian Gulf | Kuwait |
| Misool | Raja Ampat Islands | Indonesia |
| Mistaken | Lake Abitibi, Ontario | Canada |
| Mitchell | Louisiana | United States |
| Mitchell Key | Louisiana | United States |
| Mitiaro | Cook Islands | Cook Islands |
| Mitkof | Alexander Archipelago, Alaska | United States |
| Mitraha | Lake Tana | Ethiopia |
| Miyakejima | Izu Islands | Japan |
| Miyakojima | Miyako Islands part of the Sakishima Islands part of the Ryukyu Islands | Japan |
| Mjältön | High Coast | Sweden |
| Mljet | Adriatic Sea | Croatia |
| Mo-do-Meio | Beira Litoral islands | Portugal |
| Mohácsi-sziget | Danube River | Hungary |
| Mohawk | Lake Erie, Ontario | Canada |
| Mohéli | Comoros | Comoros |
| Mohni | Gulf of Finland | Estonia |
| Moho Tani | Marquesas Islands | French Polynesia |
| Île-aux-Moines | Gulf of Morbihan | France |
| Moínho | Alentejo islands | Portugal |
| Mokoia | Lake Rotorua | New Zealand |
| Molara | | Italy |
| Molène | Archipel de Molène | France |
| Molokai | Hawaii | United States |
| Møn | | Denmark |
| Moneron | Strait of Tartary, Sakhalin Oblast | Russia |
| Monhegan | Maine | United States |
| Monkey | Louisiana | United States |
| Monocanock | Susquehanna River, Pennsylvania | United States |
| Monomoy | Massachusetts | United States |
| Mont Saint-Michel | Normandy | France |
| Monte Branco | Alentejo islands | Portugal |
| Monte Farinha | Beira Litoral islands | Portugal |
| Montecristo | Tuscan Archipelago | Italy |
| Montreal | Hochelaga Archipelago | Canada |
Montserrat | Leeward Islands of the Lesser Antilles | Overseas territory of the United Kingdom |
| Monument | Shepherd Islands | Vanuatu |
| Moodie | Nunavut | Canada |
| Moon | Georgian Bay Ontario | Canada |
| Moorea | Windward Islands, Society Islands, French Polynesia | Overseas Lands of France |
| Mopelia | Windward Islands, Society Islands, French Polynesia | Overseas Lands of France |
| Moresby | Queen Charlotte Islands, British Columbia | Canada |
| Morfil | River Senegal | Senegal |
| Morgan | Louisiana | United States |
| Morraceira | Beira Litoral islands | Portugal |
| Morris | Charleston Harbor, South Carolina | United States |
| Mors | Limfjorden | Denmark |
| Mortland | Illinois River, Illinois | United States |
| Moruroa | Tuamotus, French Polynesia | France |
| Moscos Islands | Tanintharyi Region | Burma |
| Mosenthein | Mississippi River, Illinois | United States |
| Moser | Mississippi River, Missouri | United States |
| Moskenesøya | Lofoten | Norway |
| Moso | Shepherd Islands | Vanuatu |
| Mosterøy | Rennesøy municipality, Ryfylke Islands, Rogaland county | Norway |
| Mota | Banks Islands | Vanuatu |
| Mota Lava | Banks Islands | Vanuatu |
| Motiti | Bay of Plenty | New Zealand |
| Motu One | Windward Islands, Society Islands, French Polynesia | Overseas Lands of France |
| Motuihe | Hauraki Gulf | New Zealand |
| Motukaramarama | Motukawao Islands, Hauraki Gulf | New Zealand |
| Moturata | Mouth of the Taieri River | New Zealand |
| Moturua | Motukawao Islands, Hauraki Gulf | New Zealand |
| Motutapu | Hauraki Gulf | New Zealand |
| Motuwi | Motukawao Islands, Hauraki Gulf | New Zealand |
| Moucha | | Djibouti |
| Moul of Eswick | Shetland Islands | Scotland |
| Mount Ao | Zhoushan Archipelago | China |
| Mount Desert | Maine | United States |
| Mount Maji | Zhoushan Archipelago | China |
| Mousa | Shetland Islands | Scotland |
| Mouse | Bermuda | Bermuda |
| Mouse | Lake Erie, Ohio | United States |
| Moutoa | Whanganui River | New Zealand |
| Mowat | Georgian Bay (Parry Sound), Ontario | Canada |
| Muck | Inner Hebrides | Scotland |
| Muckle Green Holm | The North Isles, Orkney Islands | Scotland |
| Muckle Flugga | Shetland Islands | Scotland |
| Muckle Ossa | Shetland Islands | Scotland |
| Muckle Roe | Shetland Islands | Scotland |
| Mud | Detroit River, Michigan | United States |
| Mud Grass | Louisiana | United States |
| Mud Island Shoal | Delaware River, Pennsylvania | United States |
| Muharraq | Persian Gulf | Bahrain |
| Muhu | West Estonian archipelago; Baltic Sea | Estonia |
| Isla Mujeres | Caribbean Sea, Quintana Roo | Mexico |
| Mukawwar | | Sudan |
| Mulberry | James River, Virginia | United States |
| Mull | Inner Hebrides | Scotland |
| Mumfort | York River, Virginia | United States |
| Murano | Venetian Lagoon, Veneto | Italy |
| Murphy | Allegheny River, Pennsylvania | United States |
| Murray | Torres Strait Islands, Queensland | Australia |
| Murry | Thousand Islands, New York | United States |
| Murter | Adriatic Sea | Croatia |
| Musholm | Islands of the Great Belt | Denmark |
| Muskeget | Massachusetts | United States |
| Muskingum | Ohio River, West Virginia | United States |
| Mussau | St. Matthias Islands | Papua New Guinea |
| Mussel Rock | California | United States |
| Mustang | Port Aransas, Texas | United States |
| Mustapha | Ohio River, West Virginia | United States |
| Myingun Island | Rakhine State | Burma |
| Mykines | Faroe Islands | Denmark |
| Mykonos | Cyclades | Greece |