German Chancellor Gerhard Schroeder has congratulated Mr Blair on his election win, saying it was a victory for his progressive policies.
" I particularly wish that the UK, under your direction, can, in years to come, take the step of joining the single currency "
President of the European Parliament
"The voters have recognised your reform-friendly and responsible politics and clearly expressed their trust in you for another term of office," Mr Schroeder wrote in a letter to Mr Blair released by the Chancellery.
Mr Schroeder added: "I take pleasure in continuing our excellent co-operation given the challenges of the years to come."
The two leaders have a warm relationship based on a shared political orientation - a centrist version of socialism Mr Blair refers to as the Third Way.
The Austrian Chancellor, Wolfgang Schuessel, joined the well-wishers, saying, "Tony Blair has achieved an impressive victory."
China also congratulated Mr Blair.
"We have expressed our congratulations to Mr Blair for his re-election as prime minister," said a foreign ministry statement.
"We are confident that Sino-British relations will continue to develop thanks to the joint efforts of the two governments during the new term of the Labour party."
The President of the European Parliament, Nicole Fontaine, welcomed Mr Blair's victory, as well as his "pro-European" plans.
" There are many signs now that Labour will act for Britain to become part of EMU. That will influence Swedish policy "
Swedish Prime Minister Goeran Persson
"Thanks to the strengthened legitimacy that the universal suffrage has conferred upon you, I particularly wish that the UK, under your direction, can, in years to come, take the step of joining the single currency," she said in a statement.
"The European Commission looks forward to working with you and your colleagues in meeting the many challenges which face us as Europeans. Let us turn these challenges into opportunities for all our countries and citizens," said Romano Prodi, the President of the European Commission, after congratulating Mr Blair.
Sweden watches closely
The Swedish prime minister joined in the congratulations and said his country would be closely watching Britain's policy regarding the euro.
"There are many signs now that Labour will act for Britain to become part of European economic monetary union. That will influence Swedish policy," Prime Minister Goeran Persson was quoted by the Swedish news agency TT as saying.
" I am very pleased with the result because it is also a result which shows that many people in Britain are pro-Europe "
Belgian Prime Minister Guy Verhofstadt
Although it currently holds the rotating presidency of the European Union, Sweden - like Britain and Denmark - has so far not adopted the single European currency.
The Belgian Prime Minister, Guy Verhofstadt, told the BBC:
"I am very pleased with the result because it is also a result which shows that many people in Britain are pro-Europe - also the (good) result of the Liberal Democrats, the most pro-European political party in Britain."
He said contacts between the UK and Brussels had improved since Tony Blair became prime minister, and were now "excellent".
He added that he hoped the Labour victory would increase the chances of the UK joining the euro, but said this was a decision for British voters.
He said Mr Blair was "a good European", adding:
"I think that we shall see the increasing involvement of Mr Blair and the British Government in this whole debate on the future of Europe and that is the best thing that can happen for the European Union."