As exit polls showed a landslide for incumbent President Jacques Chirac, US Secretary of State Colin Powell said he was "pleased" to see Mr Le Pen "overwhelmingly marginalised and defeated".
EU President Romano Prodi said the French people had rejected "extremist, isolationist policies".
"Today the French people have once again demonstrated that their nation belongs to the heart of Europe," he said.
The UK Prime Minister, Tony Blair, congratulated Mr Chirac on his re-election and called the result "a victory for democracy and a defeat for extremism".
German Chancellor Gerhard Schroeder expressed similar views:
"The French people have rejected extremism without ambiguity... I am delighted that we can continue our close co-operation and wish you courage and success."
'Everyone a loser'
The defeat of Mr Pen was received a mixed welcome in Austria, where the ruling coalition already contains elements of the extreme right.
Peter Sichrovsky, a Member of the European Parliament for the far-right Freedom Party, described Mr Chirac's victory after his poor showing in the first round as a "result of losers".
"Maybe we don't like Le Pen but at least he's honest - we don't like what he says but he offers solutions, the wrong solutions," he said.
"But what about the right solutions, where are they? And the traditional political parties have to learn that voters today expect solutions, nothing else."
But the secretary general of Austria's governing conservatives, Maria Rauch-Kallat, hailed Chirac's win.
"It is very satisfying that the French have clearly rejected the racist policies of the National Front," she said.
"In this, France has clearly expressed its attachment to the European Union."
'Brilliant victory
Official reaction in Middle Eastern states with strong links to France through history and immigration has been one of delight.
"I do not need to tell you with how much satisfaction I welcome your re-election," said Algerian President Abdelaziz Bouteflika in a message to Mr Chirac.
France had regained "the glory and the prestige which have characterised the country throughout its long history", he added.
In Lebanon Prime Minister Rafiq Hariri commended the French winner on his "brilliant victory".
"France has chosen Jacques Chirac to continue working for peace in the Middle East," he said.