The City of Zagreb cooperates with various cities and associations through intercity and international relations. New contacts with sister cities are encouraged and old ones are renewed. There is also an attempt to spread cooperation with cities with which there was no previous contact. The city of Zagreb prioritizes cooperation with the following: Capitals of EU Member States Capitals of countries that are applicants or candidates for EU membership Cities with which the City of Zagreb has signed a treaty       on friendship and cooperation Capitals of EU Presidential countries World metropolis'

The City of Zagreb is a member of many intercity and international organizations, including Metropolis, Eurocities, Impacts, Assembly of European Regions and Major Cities of Europe IT Users Group and Union of Central and South Eastern European Capitals.