When Cuba became an independent republic in 1902, Switzerland recognised the new republic and established diplomatic and consular relations. The first Swiss honorary consuls to Cuba were appointed in the 19th century. The Swiss consulate was established in 1918 and gradually upgraded to a full embassy in 1957.
Trade took place as far back as the 19th century and continued after the Cuban revolution in 1959.
Switzerland represented the United States' interests in Cuba from 1961 until the resumption of diplomatic relations between the two countries in July 2015. Switzerland also represented the interests of Cuba in the United States from 1991 to July 2015.
Cuba, Historical Dictionary of Switzerland (de, fr, it):
Diplomatic Documents of Switzerland, Dodis