The city of Loimaa has six twin towns. Together with Uddevalla, Thistedt, Skien and Mosfellsbær, Loimaa forms the oldest chain of twinned towns still in operation in the Nordic countries. The twinned towns offer good opportunities for cooperation in different fields and promote, for example, international cooperation between different educational institutions.

The twin cities of Loimaa are:

• Iceland Mosfellsbær
• Norway Skien
• Sweden Uddevalla
• Denmark Thisted
• Estonia Jõhvi

Friendship with Staraja Russa in Russia has been suspended, at least for the time being.