The Emir of Qatar, Sheikh Hamad bin Khalifa Al Thani, is to hand over power to his son, the Heir Apparent Sheikh Tamim bin Hamad Al Thani.
A palace statement said that Qataris would be invited to swear allegiance to the new emir on Wednesday.
Sheikh Hamad is due to address the nation at 08:00 (05:00 GMT) on Tuesday, which will be a national holiday.
Rumours had been circulating for days that Sheikh Tamim, 33, was preparing to succeed his 61-year-old father.
Qatar-based al-Jazeera TV reported that Sheikh Hamad had told a meeting of the "ruling family and top advisers" of his decision on Monday.
The Emiri Diwan later announced that Sheikh Hamad and Sheikh Tamim would both receive Qatari citizens after the emir had addressed the nation on Tuesday, the official Qatar News Agency reported.
On Wednesday morning, they would also receive citizens wanting "to swear allegiance to His Highness Sheikh Tamim bin Hamad Al Thani as emir of Qatar", it added.
A cabinet reshuffle is also expected as part of the changes in the government line-up, with younger ministers likely to take charge. It is not clear if the long-serving Prime Minister and Foreign Minister, Sheikh Hamad bin Jassim Al Thani, will also step aside.
Qatar has been dominated by the Al Thani family for almost 150 years.
Sheikh Hamad seized power from his father Sheikh Khalifa in a bloodless coup in 1995, with the support of the armed forces and cabinet, and also neighbouring states.
Since then the emir has introduced some political and economic liberalisation, and in recent years has made Qatar a major player in regional diplomacy.
In 2003, he named Sheikh Tamim - his second son by his second wife Sheikha Moza bint Nasser - as his heir apparent. He replaced his elder brother, Sheikh Jassim Bin Hamad Al Thani.
Analysts say the British-educated Sheikh Tamim, who is deputy commander-in-chief of the armed forces, is unlikely to deviate far from his father's policies.
He chairs the 2030 Vision project which outlines the development goals for the country and has a clear liberalising social agenda. The project has had significant input from his father and mother.
Sheikh Tamim is also head of the Qatar 2022 Supreme Committee, which is in charge of preparing the emirate to host the 2022 Fifa World Cup.
In foreign policy, the emirate is expected to maintain its alliance with the West while at the same time pursuing an activist stance in Syria and other Arab countries.
However, he will also inherit strained relations with some of Qatar's Gulf neighbours, notably Bahrain and the United Arab Emirates (UAE), who have been angered by Qatar's perceived closeness to the influential regional Islamist movement, the Muslim Brotherhood.
The emirate has also tried to increase its diplomatic prestige further afield. Earlier this month, Afghanistan's Taliban movement opened its first office in the capital Doha to facilitate peace talks with the United States.