"Unbelievable!" Malik shouted, leading the family in chanting, "Obama's coming, make way!"
Obama's step-grandmother and other relatives also poured out of the family homestead to salute a man seen by many Kenyans as a "son of the soil." Kenyan President Mwai Kibaki declared a public holiday on Thursday in honor of Obama.
Many stayed up all night or woke before dawn to celebrate his victory. Obama's relatives and other villagers gathered around a TV set up in a garden in Kogelo, rejoicing and pumping their arms in the air.
Across Africa, many are hoping an Obama presidency will help the vast continent, the poorest in the world. Obama's victory was also likely to seal America's reputation in the minds of many Africans as a land of staggering opportunity.
"He's in!" said Rachel Ndimu, 23, a Kenyan business student who joined hundreds of others for an election party at the residence of the U.S. ambassador to Kenya, Michael Ranneberger, which began at 5 a.m.
"I think this is awesome, and the whole world is backing him," Ndimu said as people raised glasses of champagne.
For South Africa's first black president, Nelson Mandela, the election of America's first is a symbol of hope.
"Your victory has demonstrated that no person anywhere in the world should not dare to dream of wanting to change the world for a better place," Mandela said in a letter of congratulations to Obama.
Former U.N. Secretary-General Kofi Annan, who is from the West African nation of Ghana, said the vote was a historic event that he had never expected to see in his lifetime. He said Obama's victory demonstrates "America's extraordinary capacity to renew itself and adapt to a changing world."
In Uganda, university students burned tires and hoisted bottles of beer in celebration. Amos Kisita, holding up an Obama poster in a suburb of the capital, Kampala, said he was going to celebrate for "two days, nonstop."
Obama was born in Hawaii, where he spent most of his childhood reared by his mother, a white American from Kansas. He barely knew his late father. But that has not stopped "Obamamania" from sweeping the continent, and particularly Kenya, where his picture adorns billboards and minibuses.
"If it were possible for me to get to the United States on my bicycle, I would," said Joseph Ochieng, a 36-year-old carpenter who celebrated in Nairobi's Kibera shantytown, one of Africa's largest slums.
Samuel Ouma, 36, said Obama's victory alleviated some of the pain suffered in December after Kenya's disastrous presidential election, which unleashed weeks of violence here.
Ranneberger, the U.S. ambassador, said Kenyans' love for Obama was palpable.
"With the media coverage over the past few weeks, I sometimes thought this was a Kenyan election," he told more than 500 people who gathered at his home, watching flat-screen TVs set up in the sprawling garden.
Gibson Gaitho, 14, said he does not believe an Obama presidency will change his life, but he said he was inspired by the incredible rise of a man with Kenyan roots.
"As Kenyans we feel proud," said Gaitho, who watched the results with scores of other schoolchildren at Ranneberger's party before heading back to class on a school bus. "Because of Obama, I know -- you work hard, you achieve."
Tendai Biti, an opposition leader in Zimbabwe, said Obama's victory was inspiring and so was the concession by John McCain, whose fellow Republican George W. Bush will leave the White House on Jan. 20.
"If in Africa, incumbents would accept defeat and would graciously depart from the seat of power, this would be a different continent, and indeed Zimbabwe would be a different place," said Biti, whose party is deadlocked in power-sharing talks with Zimbabwean President Robert Mugabe.
Associated Press writers Elizabeth A. Kennedy and Tom Odula in Nairobi, Kenya, Donna Bryson in Johannesburg, South Africa and Frank Jordans in Geneva, contributed to this report.