Addis Ababa, EthiopiaÃ‚Â (BBC) – The entire $200m (Ã‚Â£127m) project was funded by China as a gift to the AU, as Beijing continues to strengthen its influence in Africa.
In front of African leaders a huge golden key was handed over and the 100m high building was officially opened.
The tower overlooks a vast conference centre where African heads of state are expected to meet for years to come.
Their first AU summit in the building will take place on Sunday.
China’s most senior political adviser, Jia Qinglin, attended the opening of the new headquarters.
“The towering complex speaks volumes about our friendship to the African people, and testifies to our strong resolve to support African development,” he said, according to AFP.
The AU chairman, Equatorial Guinea’s President Teodoro Obiang Nguema, said the complex was “a reflection of the new Africa,” the agency reports.
The new AU building dominates the skyline of Addis Ababa and is the city’s tallest building.
Most of the materials used were imported from China and even the furnishings were paid for by Beijing, AFP news agency reports.
Construction began in January 2009 and involved 1,200 Chinese and Ethiopian workers.
The project coordinator, Fantalum Michael, says the new building signifies China’s growing friendship with Africa.
“It’s a testimony that this relationship will continue in the future,” he told AFP.Ã‚Â
Trade between China and Africa has increased more than six-fold during the past decade to $120bn (Ã‚Â£76bn) in 2011.
China is interested in Africa’s natural resources and in return is investing huge sums in African infrastructure.
Roads are being built by Chinese firms at a staggering rate, says the BBC’s Will Ross in Addis Ababa.
While other rich nations impose conditions before aid is given, China’s relationship with African countries is strictly a business one, he says.
Human rights groups have criticised China for undermining efforts by western countries to link aid to improvements in governance.
However African leaders have welcomed the Chinese approach and have embraced investment from Beijing.
In Ethiopia, many jobs have been created through Chinese-funded projects.
Chinese cars are being made in Ethiopian factories and China is also building a light railway across Addis Ababa.