Students from any country cannot register for IOAA directly. They are advised to contact organizers of the National Olympiad programme in their respective country. Links for National Olympiad Programmes of every participating country are listed below. If your country is not listed here, contact organizers for further information.
- Armenia
- Australia
- Austria
- Azerbaijan
- Bangladesh
- Belarus
- Bolivia
- Brazil
- Bulgaria
- Canada
- Chile
- China
- Colombia
- Croatia
- Cyprus
- Czech Republic
- Ecuador
- El Salvador
- Estonia
- France
- Georgia
- Germany
- Greece
- Hungary
- India
- Indonesia
- Iran
- Italy
- Japan
- Kazakhstan
- Kyrgyzstan
- Laos
- Latvia
- Lithuania
- Malaysia
- Mali
- Mexico
- Moldova
- Nepal
- Netherlands
- North Macedonia
- Norway
- Pakistan
- Paraguay
- Philippines
- Poland
- Portugal
- Qatar
- Romania
- Russia
- Saudi Arabia
- Serbia
- Singapore
- Slovakia
- Slovenia
- South Africa
- South Korea
- Sri Lanka
- Sweden
- Thailand
- Turkey
- Ukraine
- United Arab Emirates
- United Kingdom
- United States of America
- Vietnam