The EU on Sunday hailed the victory of Greens-backed candidate Alexander Van der Bellen over his far-right opponent in Austrian presidential elections as bolstering European unity at a time of many challenges.
"It is my pleasure to extend my wholehearted congratulations on your election ... On behalf of the European Council and personally, I wish you every success," Council head Donald Tusk said in a statement.
"At a time when we are faced with many difficult challenges, the continued constructive contribution of Austria to finding common European solutions and keeping our European unity will remain essential," Tusk said in a statement.
Public television projections gave Van der Bellen 53.3 percent of the vote against 46.7 percent for Norbert Hofer of the anti-immigration Freedom Party.
Polls had suggested the outcome would be very close, as in the first poll in May, stoking fears Hofer could become the European Union's first far-right leader and so give growing anti-establishment sentiment a major boost after Britain's shock Brexit vote in June and Donald Trump's victory.
Earlier, European Parliament head Martin Schulz hailed the outcome as a "heavy defeat of nationalism and anti-European, backward-looking populism".
"Congratulations to @vanderbellen who won the presidential election with a clear pro-European message and campaign," Schulz said in a tweet.