President Pervez Musharraf will stand down as head of the Pakistani army on Wednesday, his spokesman Rashid Qureshi has told the BBC.
The spokesman told the BBC President Musharraf would then be sworn in for another term in office on Thursday.
President Musharraf has been under intense international and domestic pressure to give up his military role.
He seized power in a coup in 1999, deposing the civilian government of Prime Minister Nawaz Sharif.
Gen Musharraf's main international backer, the United States, has grown concerned in recent months at the army's inability to rein in pro-Taleban militants and by Gen Musharraf's growing unpopularity.
It had been backing talks between President Musharraf and former Prime Minister Benazir Bhutto, who heads the country's largest political party, for a power-sharing deal.
But in recent days Ms Bhutto has said that she could not work with Gen Musharraf.
Pervez Musharraf "will take over as the president of Pakistan as a civilian" on Thursday, spokesman Gen Qureshi told BBC World TV.
Nawaz Sharif returned from exile on Sunday
He said President Musharraf would hand over his post of army chief to his deputy - Lt Gen Ashfaq Pervez Kiani - in a ceremony on Wednesday.
Asked if President Musharraf was severing all his professional links with the military, Gen Qureshi pointed out that he would remain supreme commander of the armed forces, as was the case with heads of state in other countries.
Gen Musharraf designated Gen Kiani, a former head of the intelligence services, as his successor as army head in October.
As a civilian president, Mr Musharraf would still have considerable powers, including the power to sack a civilian government.
The man he toppled in the coup, Nawaz Sharif, returned to Pakistan after years of exile on Sunday.
Mr Sharif and Benazir Bhutto have each served two terms as prime minister. Under current law that would bar them from being prime minister for a third term.
Both leaders have now filed nomination papers to contest parliamentary elections due in January.
But both are holding onto the option of boycotting the elections if they deem that they will not be free and fair.
Gen Musharraf imposed emergency rule on 3 November in order, he said, to rein in the judiciary and deal with a growing threat from Islamist militants.
Thousands of political opponents were arrested, TV and radio news was banned and judges seen to be a threat to the government were sacked.