The City of Zagreb cooperates with the neighbouring municipalities and cities, with other cities, municipalities and counties of the RC, as well as with other local and regional self-administration units in other countries.

The priority of the international activities of the City of Zagreb is the cooperation with:

- the capital cities of the EU members
- the capital cities of the countries that are candidates for the EU membership
- the main cities in the region
- the cities with which the City of Zagreb signed and agreement on partnership (friendship) and cooperation
- the world’s leading cities

Through cooperation with the capital cities of the EU member states, special attention will be dedicated to exchanging experience in organizing and managing cities, developing city technologies, transport, environmental protection, constructing computerized infrastructure, organizing and managing city-owned companies, encouraging economic activities and entrepreneurship, and using development and research support from the EU funds; special emphasis will be put on developing cooperation with the capital cities of the countries that became members of the European Union in 2004.

By establishing cooperation with the cities with which the City of Zagreb concluded an agreement on partnership and cooperation, special efforts will be made to establish priorities and define cooperation with the sister cities on the basis of the existing agreements and by proposing new agreements on partnership and cooperation; these are the cities with which the City of Zagreb signed the Agreement on Partnership and Cooperation: Vienna, Budapest, Krakow, Kyoto, Lisbon, Ljubljana, Mainz, Pittsburgh, Sarajevo, Shanghai, St. Petersburg and Tromsǿ.

The City of Zagreb has been active on the international plan through its membership in international and intercity organizations and associations (The Assembly of the European Regions – AER, Metropolis, Euro-cities, Major Cities of Europe IT Users' Group, Impacts, Union of the capital cities of the central and south-eastern Europe…) and by participating in numerous international conferences on the development and advancing local self-administration and on the projects important for the development of the cities.