The landmark visit to Obama's ancestral homeland of Kenya, where his father was born, is his first as president, and is also the first time a sitting US president will visit Ethiopia and the AU's headquarters in Addis Ababa.
The first African-American president of the US is expected to address regional security issues and trade, and also touch on matters relating to democracy, poverty, and human rights in the region.
'Fastest-growing markets'
Joining him on the trip is National Security Adviser Susan Rice, foreign policy aide Ben Rhodes and White House spokesman Josh Earnest.
Before heading off for the trip, Obama's fourth to Africa since taking office, he spoke about the promise of, and difficulties on, the continent.
"Despite its many challenges - and we have to be clear-eyed about all the challenges that the continent still faces - Africa is a place of incredible dynamism, some of the fastest-growing markets in the world, extraordinary people, extraordinary resilience," Obama said.
While speaking at an event for the African Growth Opportunity Act, US trade legislation which aims to help bolster Africa's prosperity, the president said the continent "has the potential to be the next centre of global economic growth".
President Obama has travelled to Africa more than any other sitting US president, and talked about the "deep" ties between Africa and his country before setting off on the trip.
"There have been times where there have been misunderstandings, and there have been times where there have been suspicions," he said.
"But when you look at every survey, it turns out that the people of Africa love the United States and what it stands for."
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| Obama has travelled to Africa more times than any other sitting US president [Reuters] |
Democratic deficit
Obama's trip has also come under fire by rights groups, and more than 50 African and global human rights organisations have called on him to publicly meet democracy activists on the trip.
They voiced concerns about "grave and worsening" rights challenges in both Kenya and Ethiopia.
The charges against Kenyatta, and the fact that Ethiopia's government won 100 percent of parliamentary seats in a recent disputed election, has raised questions about whether Obama should have made the trip at all.
In Kenya, Obama will attend a Global Entrepreneurship Summit, aimed at promoting businesses that promise to lift many more Africans out of poverty and help insulate societies against radicalisation.
In Addis Ababa, Obama is expected to address leaders of the African Union, remarks that may touch on Africa's democratic deficit.
There are no official visits scheduled for Obama to see his relatives while in Kenya, officials said.
Obama has said he had "never truly known" his father, who was born in Kenya's far west, in a village near the equator and the shores of Lake Victoria.
