Several European politicians have welcomed Van der Bellen's win at the polls. Germany's head of state described the Greens-backed politician as a "convinced European" as Austria copes with a budding right-wing movement.
German Foreign Minister Frank-Walter Steinmeier on Monday responded positively to news that former Greens party leader Alexander Van der Bellen had won Austria's presidential elections after absentee votes were counted.
Van der Bellen had run as an independent, but with massive backing from the Greens party.
"The whole of Europe has heaved a sigh of relief," the German Foreign Office quoted Steinmeier as saying.
With less than a percentage point, Van der Bellen edged out far-right contender Norbert Hofer with 50.3 percent of the vote following a contentious election.
German President Joachim Gauck described the independent politician, who was backed by Austria's Greens party, as a "convinced European" working for a "strong, steady and - in the long run - stronger European Union."
Czech Defense Minister Martin Stropnicky, a member of the centrist ANO party, also welcomed Van der Bellen's win, saying it was an "important victory for Europe."
However, the presidential election pitted two unconventional politicians in the run-off, making it a difficult choice for voters accustomed to Austria's Social Democrats and its conservative counterpart the People's Party.
Sylvia Gloggnitzer, an Austrian bank teller, told DW's Bernd Riegert that choosing between both candidates was difficult for the entire country.
"What many Austrians are naturally conscious of, and why so many have chosen Hofer is that we cannot save the world by ourselves," Gloggnitzer said.
Hofer of the far-right Freedom Party campaigned on an anti-immigrant platform after Austria received roughly 90,000 migrants in 2015, many fleeing war in the Middle East, Asia and Africa.
In February, Vienna announced a cap on migrants entering the country, limiting those transiting through the country to 32,000 per day and others claiming asylum to 80 per day.
But Austria's president-elect said in a low-key victory speech that his goal in office is to assure his fellow citizens about their country's future.
"My aim is to be a constructive partner of the federal government and the parliament so that in six years, people in Austria feel better and that people will be able to say: 'My children have a good future,'" he added.
ls/bw (DW, AP, dpa)