South Africa President Jacob Zuma was one of the first to congratulate Obama, saying in a statement: "We value our relations with the United States and look forward to strengthening bilateral cooperation in the years to come.”
"South Africa is confident that the United States will continue to play a positive role in this regard," he added.
Kenyan President Mwai Kibaki told Obama that people in his ancestral homeland were celebrating his "well deserved victory".
"Kenya, as always is proud of our association with you," Kibaki said in a statement. "We look forward to the deepening of relations between our two countries during your second term in office."
"The reason why he has won is because God has given it to him," said Sarah Obama, 90 this year and the third wife of the paternal grandfather of the president, who has said he regards her as a grandmother.
German Chancellor Angela Merkel wrote to Obama to congratulate him on his re-election and hailed their cooperation to beat the global economic crisis. "I have deeply appreciated our many meetings and conversations about all the issues involved in developing the German-American and the transatlantic relationship, not least in overcoming the global financial and economic crisis," she wrote in a letter released by her office.
French President Francois Hollande hailed Obama's re-election, and said it meant the United States would be totally committed on the world stage. Obama's victory meant a "clear choice for an open, united America that is totally engaged on the international scene", he said.
It would "once again reinforce our partnership to facilitate the return of economic growth in our countries, to fight unemployment, and to find solutions to crises that threaten us, notably in the Middle East", he added.
Hollande, who had openly expressed his backing for Obama, said the US leader's new term would be marked "by the same spirit of dialogue, esteem and respect". It would further buttress "the friendship and the [mutual] confidence which unite us", he added.
The Socialist leader said the victory was "an important moment for the United States and also for the world".
Middle East peace efforts
Palestinian President Mahmoud Abbas also extended his congratulations to the US leader and called on him to pursue Middle East peace efforts.
Abbas "congratulated US President Barak Obama on his re-election as US president for a second term," said a statement carried by official news agency WAFA. "The president hopes that Obama continues his efforts to achieve peace in the Middle East."
In Afghanistan, where the US has some 68 000 troops helping the government fight a Taliban insurgency, President Hamid Karzai said he hoped Obama's re-election would lead to an expansion of relations between the two countries.
"The president of Afghanistan hopes that with President Obama's re-election relations between Afghanistan and the United States, based on bilateral interests, are further expanded," his spokesperson Aimal Faizi told AFP.
Israel Prime Minister Benjamin Netanyahu extended his congratulations to Obama, saying ties between their two countries were "stronger than ever".
"I will continue to work with President Obama to ensure the vital security interests of Israel and the United States," Netanyahu added, saying he would meet later Wednesday with US ambassador to Israel Dan Shapiro.
Russian President Vladimir Putin sent Obama a telegram congratulating him on his victory. The Kremlin received the news of Obama's victory over Mitt Romney "very positively", spokesperson Dmitry Peskov told Russian news agencies.
Also in a telegram, Egypt's President Mohamed Morsi on Wednesday hailed his US counterpart’s re-election and said he hoped it would strengthen the "friendship" between their two countries.
Morsi hoped for a "strengthening of the friendship between the two countries to serve their common interests, namely justice, freedom and peace," read a telegram released by the official news agency.
The Nelson Mandela Centre of Memory also congratulated Obama on his election.
"On behalf of our founder [former president] Nelson Mandela and our board of trustees, we congratulate you upon your re-election," spokesperson Sello Hatang said in a statement.
He said the US was a vital partner in Africa's efforts to overcome poverty and inequality.
"We are confident that under your continued, insightful leadership this partnership will grow stronger, both in working with governments on the continent, but also with the burgeoning civil society movements that seek to empower communities." – AFP & Sapa