As a member of the noble Russian Van der Bellen family of Dutch ancestry, he was born in Austria to aristocratic Russian and Estonian parents who were refugees of Stalinism, and became a naturalised Austrian citizen together with his parents in 1958.
Van der Bellen, who is known privately by the nickname “Sascha” (a Russian diminutive of Alexander), was born in Vienna, the son of Alexander Konstantin (1898–1966), and Alma (née Siibold [Siebold, Sieboldt]; 1907–1993). His father was an aristocratic Russian-born banker of Baltic German, Russian German, Dutch, and Estonian descent, while his mother was Estonian.
The Van der Bellen family is descended from Johann Abraham van der Bellen, who was born in the Netherlands and who moved to the Russian Empire in the 18th century, and who volunteered for service at a hospital in Moscow and who later became a military doctor in Pskov. In Russia, the family was recognized as noble in the early 19th century and many family members held prominent roles in the local government of Pskov. Van der Bellen’s grandfather, Aleksander von der Bellen (1859–1924), was a liberal politician who was head of the local Pskov government before 1918 when the Imperial German Army invaded Pskov during the Russian Civil War. In the summer of 1919, when Pskov was briefly occupied by the Estonian Army, Van der Bellen’s grandparents, father, and uncles fled the advancing Bolshevik Red Army and settled in the newly independent Estonia.
The surname was spelled “von der Bellen” in Imperial Russia, with “von der” being a nobiliary particle. The family changed the spelling of the name to the Dutch “Van der Bellen” (formerly also “Van-Der-Bellen”) in Estonia, where all privileges of the nobility had been abolished, and where the use of the German particle von as an indicator of noble origin in surnames (as was common in Russia) was illegal.