Ashraf Ghani won Afghanistan's disputed presidential election decisively with 55% of the vote, results revealed on Friday, after the figure was kept secret for five days over concerns that fraud allegations could trigger violence.
Ghani and Abdullah both claimed victory in the June 14 run-off vote, tipping the country into a political crisis that the United Nations feared could descend into the ethnic unrest of the 1990s civil war.
A "unity government" deal was finally agreed on Sunday, with Ghani serving as the next president and Abdullah taking up the new role of chief executive, similar to that of prime minister.
The Independent Election Commission (IEC) had declared Ghani the winner, but did not reveal the margin of victory or the turnout to avoid stoking bitter resentment among Abdullah's supporters who believed he won fairly. At an IEC ceremony on Friday, Ghani was presented with a certificate that confirmed he had won 55.27% of the ballot on a turnout of 7.12 million voters.
Ghani hailed the unity government as a turning point for Afghanistan as US-led combat troops wind down their 13-year war against the Taliban.
"The political transition was a success for the nation and we can move forward," he said after accepting the certificate.
"We call for investors to come to Afghanistan."
The election was marred by widespread fraud, repeating serious problems seen in previous elections since the Taliban regime was ousted from power in 2001.
After the UN-supervised audit, 1,206 of the 22,828 ballot boxes were invalidated -- meaning several hundred thousand votes were thrown out.
Ghani said he would prioritise electoral reform to improve future elections, and thanked outgoing President Hamid Karzai, who has ruled since the fall of the Taliban.
Ghani will be inaugurated in Kabul on Monday in Afghanistan's first democratic transfer of power.