0341 GMT July 17, 2018
The professorial Van der Bellen was sworn in Thursday, vowing that he would do his best to implement Austria’s constitution.
"I promise to follow faithfully the constitution and all laws of the republic and to fulfill my role to the best of my knowledge and conscience," said Van der Bellen during a ceremony in Austria’s parliament.
The 73-year-old went through ups and downs to become Austria’s federal head of state at a time when many feared the rise of Norbert Hofer from the Freedom Party (FPOe) as the first far-right president in the European Union. Hofer, like many other nationalists in Europe, had largely benefited from anti-immigration sentiments.
Van der Bellen won a run-off against Hofer in May, but a court annulled the results over procedural irregularities. The two had been slated to contest a re-run in October but it was postponed to early December and Van der Bellen won the largely ceremonial, but coveted presidency.
Australia’s ecologist Greens backed Van der Bellen although he ran as an independent. However, the government would be a "grand coalition" including Chancellor Christian Kern’s center-left Social Democrats (SPOe) and the center-right People's Party (OeVP).
Speculations have raged about the future of the government which is due to rule until late 2018. Reports have emerged about squabbling within the coalition while many have raised the possibility for early election due to FPOe good standing in opinion polls.