IMO currently has 175 Member States and three Associate Members
Albania
| 1993
| Lithuania | 1995 |
| Algeria | 1963 | Luxembourg | 1991 |
| Angola | 1977 | Madagascar
| 1961 |
| Antigua and Barbuda | 1986 | Malawi
| 1989 |
| Argentina | 1953 | Malaysia | 1971 |
| Armenia | 2018 | Maldives | 1967 |
| Australia | 1952 | Malta | 1966 |
Austria
| 1975 | Marshall Islands | 1998 |
| Azerbaijan | 1995 | Mauritania | 1961 |
| Bahamas | 1976 | Mauritius | 1978 |
| Bahrain | 1976 | Mexico | 1954 |
| Bangladesh | 1976 | Monaco | 1989 |
| Barbados | 1970 | Mongolia | 1996 |
| Belarus | 2016 | Montenegro | 2006 |
| Belgium | 1951 | Morocco | 1962 |
| Belize | 1990 | Mozambique
| 1979 |
| Benin | 1980 | Myanmar | 1951 |
| Bolivia (Plurinational State of) | 1987 | Namibia | 1994 |
| Bosnia and Herzegovina | 1993
| Nauru | 2018 |
| Botswana | 2021 | Nepal
| 1979
|
| Brazil | 1963 | Netherlands
| 1949
|
| Brunei Darussalam | 1984 | New Zealand
| 1960
|
| Bulgaria | 1960 | Nicaragua
| 1982
|
| Cabo Verde | 1976 | Nigeria
| 1962
|
| Cambodia | 1961 | North Macedonia
| 1993
|
| Cameroon | 1961 | Norway
| 1958
|
| Canada | 1948 | Oman
| 1974
|
| Chile | 1972 | Pakistan
| 1958
|
| China | 1973 | Palau
| 2011
|
| Colombia | 1974 | Panama
| 1958
|
| Comoros | 2001 | Papua New Guinea
| 1976
|
| Congo | 1975 | Paraguay
| 1993
|
| Cook Islands | 2008 | Peru
| 1968
|
| Costa Rica | 1981 | Philippines
| 1964
|
| Côte d'Ivoire | 1960
| Poland
| 1960
|
| Croatia | 1992 | Portugal
| 1976
|
| Cuba | 1966 | Qatar
| 1977
|
| Cyprus | 1973 | Republic of Korea
| 1962
|
| Czechia | 1993 | Republic of Moldova
| 2001
|
| Democratic People's Republic of Korea | 1986 | Romania
| 1965
|
| Democratic Republic of the Congo | 1973 | Russian Federation
| 1958
|
| Denmark | 1959 | Saint Kitts and Nevis
| 2001
|
| Djibouti | 1979 | Saint Lucia
| 1980
|
| Dominica | 1979 | Saint Vincent and the Grenadines
| 1981
|
| Dominican Republic | 1953 | Samoa
| 1996
|
| Ecuador | 1956 | San Marino
| 2002
|
| Egypt | 1958 | Sao Tome and Principe
| 1990
|
| El Salvador | 1981 | Saudi Arabia
| 1969
|
| Equatorial Guinea | 1972 | Senegal
| 1960
|
| Eritrea | 1993 | Serbia
| 2000
|
| Estonia | 1992 | Seychelles
| 1978
|
| Ethiopia | 1975 | Sierra Leone
| 1973
|
| Fiji | 1983 | Singapore
| 1966
|
| Finland | 1959 | Slovakia
| 1993
|
| France | 1952 | Slovenia
| 1993
|
| Gabon | 1976 | Solomon Islands
| 1988
|
| Gambia | 1979 | Somalia
| 1978
|
| Georgia | 1993 | South Africa
| 1995
|
| Germany | 1959 | Spain
| 1962
|
| Ghana | 1959 | Sri Lanka
| 1972
|
| Greece | 1958 | Sudan
| 1974
|
| Grenada | 1998 | Suriname
| 1976
|
| Guatemala | 1983 | Sweden
| 1959
|
| Guinea | 1975 | Switzerland
| 1955
|
| Guinea-Bissau | 1977 | Syrian Arab Republic
| 1963
|
| Guyana | 1980 | Thailand
| 1973
|
| Haiti | 1953 | Timor-Leste
| 2005
|
| Honduras | 1954 | Togo
| 1983
|
| Hungary | 1970 | Tonga
| 2000
|
| Iceland | 1960 | Trinidad and Tobago
| 1965
|
| India | 1959 | Tunisia
| 1963
|
| Indonesia | 1961 | Türkiye
| 1958
|
| Iran (Islamic Republic of) | 1958 | Turkmenistan
| 1993
|
| Iraq | 1973 | Tuvalu
| 2004
|
| Ireland | 1951 | Uganda
| 2009
|
| Israel | 1952 | Ukraine
| 1994
|
| Italy | 1957 | United Arab Emirates
| 1980
|
| Jamaica | 1976 | United Kingdom of Great Britain and Northern Ireland
| 1949
|
| Japan | 1958 | United Republic of Tanzania
| 1974
|
| Jordan | 1973 | United States of America
| 1950
|
| Kazakhstan | 1994 | Uruguay
| 1968
|
| Kenya | 1973 | Vanuatu
| 1986
|
| Kiribati | 2003 | Venezuela (Bolivarian Republic of)
| 1975
|
| Kuwait | 1960 | Viet Nam
| 1984
|
| Latvia | 1993 | Yemen
| 1979
|
| Lebanon | 1966 | Zambia
| 2014
|
| Liberia | 1959 | Zimbabwe
| 2005
|
| Libya | 1970 |
|
|
*Table continues on the right Associate Members:
| Faroes | 2002 |
Hong Kong, China
| 1967 |
| Macao, China | 1990
|