47 Members (excluding the associate or suspended members but including the countries represented on their behalf) [The rulers are not necessarily the representatives in the organisation. ] :
| | UNITED ARAB EMIRATES | (Abu Dhabi ar) | | President Sheikh Khalifa bin Zayed Al Nahyan | | |
| | BANGLADESH | (Dhaka a) | | President Abdul Hamid | | |
| | BAHRAIN | (Manamah) | | King Sheikh Hamad bin Isa Al Khalifah | | |
| | BRUNEI DARUSSALAM | (Bandar Seri Begawan) | | Sultan Hassanal Bolkiah | | |
| | BOTSWANA | (Gaborone) | | President Mokgweetsi Masisi | | |
| | CAMEROON | (Yaounde) | | President Paul Biya | | |
| | CHINA | (Beijing) | | Xi Jinping | | |
| | CYPRUS | (Nicosia) | | President Nicos Anastasiades | | |
| | EGYPT | (Cairo a + Alexandria r + Almasa New Capital City f) | | President Abdel Fattah el-Sisi | | |
| | GHANA | (Accra) | | President Nana Addo Dankwa Akufo-Addo | | |
| | THE GAMBIA | (Banjul) | | President Adama Barrow | | |
| | INDONESIA | (Jakarta a + Bogor r + Chipanas r + Yogyakarta r + Tampaksiring r) | | President Joko Widodo | | |
| | INDIA | (New Delhi a + Simla s + Bolarum w) | | President Ram Nath Kovind | | |
| | IRAQ | (Baghdad) | | President Barham Salih | | |
| | IRAN | (Tehran) | | Supreme Leader Ayatollah Ali Khamenei | | |
| | JORDAN | (Amman) | | King Abdullah II | | |
| | JAPAN | (Tokyo) | | Emperor Naruhito | | |
| | KENYA | (Nairobi) | | President Uhuru Kenyatta | | |
| | NORTH KOREA | (Pyongyang a) | | Kim Jong-Un | | |
| | SOUTH KOREA | (Seoul adknr + Sejong b) | | President Moon Jae-In | | |
| | KUWAIT | (Kuwait City) | | Emir Sheikh Nawaf Al Ahmad Al Jabir Al Sabah | | |
| | LEBANON | (Beirut a + Baabda r + Hadeth d) | | President Michel Aoun | | |
| | SRI LANKA | (Sri Jayewardenepura Kotte al + Colombo ejnr + Kandy r) | | President Gotabaya Rajapaksa | | |
| | LIBYA | (Tripoli a) | | Fayez El-Sarraj | | |
| | MYANMAR | (Naypyidaw a + Rangoon bn) | | President Win Myint | | |
| | MONGOLIA | (Ulan-Bator) | | President Khaltmaagiin Battulga | | |
| | MAURITIUS | (Port Louis a + Reduit in Moka r) | | President Prithvirajsing Pradeep Roopun | | |
| | MALAYSIA | (Putrajaya aj + Kuala Lumpur ejlry) | | Sultan Abdullah Shah | | |
| | NIGERIA | (Abuja a) | | President Muhammadu Buhari | | |
| | NEPAL | (Kathmandu) | | President Bidhya Devi Bhandari | | |
| | OMAN | (Muscat) | | Sultan Haitham bin Tarik | | |
| | PAKISTAN | (Islamabad) | | President Arif Alvi | | |
| | PALESTINE | (Ramallah qr + (East Jerusalem)) | | President Mahmoud Abbas | | |
| | QATAR | (Doha) | | Emir Sheikh Tamim bin Hamad Al Thani | | |
| | SAUDI ARABIA | (Riyadh) | | King Salman | | |
| | SUDAN | (Khartoum) | | Abdel-Fatah al-Burhan Abdelrahman | | |
| | SINGAPORE | (Singapore) | | President Halimah Yacob | | |
| | SIERRA LEONE | (Freetown) | | President Julius Maada Wonie Bio | | |
| | SENEGAL | (Dakar) | | President Macky Sall | | |
| | SOMALIA | (Mogadishu-Hamar Weyne) | | President Mohamed Abdullahi Mohamed Farmajo | | |
| | SYRIA | (Damascus) | | President Bashar Al-Assad | | |
| | THAILAND | (Bangkok) | | King Rama X. Vajiralongkorn | | |
| | TURKEY | (Ankara a + Marmaris s) | | President Recep Tayyip Erdogan | | |
| | TANZANIA | (Dodoma City aln + Dar Es Salaam jnqr) | | President John Magufuli | | |
| | UGANDA | (Kampala a + Entebbe r) | | President Yoweri Museveni | | |
| | YEMEN | (Riyadh x) | | President Abd Rabbuh Mansur Hadi | | |
| | SOUTH AFRICA | (Pretoria ae + Cape Town l + Bloemfontein j + Johannesburg d) | | President Cyril Ramaphosa | | |