Kalmar Union–Sierra relations

Kalmar Union–Sierra relations refers to the international relations between the Kalmar Union and the Kingdom of Sierra. Diplomatic interactions between the two powers date back to Sierra's historic relations with the Kalmar Union's predecessor states (,, , and ) during the late 19th century. Since 1951, Kalmar Union and Sierra have maintained diplomatic missions to each other's respective capitals and have generally amicable relations.

Both nations are constitutional monarchies and are members together in numerous international organizations and agreements including the League of Nations and the. The two states have cooperated together through a free trade agreement, mutual visa waiver programs, and mutual extradition agreements. In addition, both are leading partners in combatting global terrorism and other crimes, and are committed towards fostering peace, security, and economic development.

According to a 2016 RBS General Survey poll, 89% of Sierrans had a positive view of Kalmar Union, while a similar poll showed higher figures at 92% with regards to Kalmar leadership. According to the K.S. Royal Bureau of Census, there were approximately 33,000 Sierran expatriates living in Kalmar Union, while over 15% of Sierrans have ancestries originating from Kalmar Union.