Kuwait's ruler will be sworn in as a new emir on Sunday, after a parliament vote considered to be a formality.
Sabah's accession ends days of uncertainty about the future
Sheikh Sabah al-Ahmad al-Sabah was nominated by the cabinet on Tuesday, ending a serious crisis within the ruling family over the succession.
He replaces his ailing cousin, Sheikh Saad al-Abdullah, who was considered too sick to become head of state.
Sheikh Sabah, who has been the oil-rich state's prime minister since 2003, has one year to choose his own successor.
His cabinet unanimously asked him to take charge and analysts say there is no doubt that parliament will give him the simple majority he needs to become emir on Sunday.
A swearing-in ceremony has been scheduled for shortly after the vote.
On Tuesday, parliament voted 65-0 to depose Sheikh Saad on health grounds, the first time a Gulf parliament has been called on to play such a constitutional role.
Choice of heir
SHEIKH SABAH AL-AHMAD
Born in 1929
Foreign minister for 40 years, 1963-2003
Prime minister with executive powers since 2003
The selection of a new crown prince is a major question left hanging over Kuwait after the historic parliament and cabinet votes.
Sheikh Sabah's choice of heir will be closely watched, as his accession has broken a long tradition of alternating power between the two rival wings of the Sabah dynasty.
In addition, the emir has the right to appoint a prime minister, and Sheikh Sabah has been urged by some MPs to appoint someone from outside the ruling family.
Analysts say the affair has broken a long-held taboo on discussing the health of Gulf rulers, as well as blazed a constitutional trail that has strengthened the role of Kuwait's elected parliament.
Sheikh Sabah is a reformist minded statesman who has pushed ahead with enfranchising women and economic liberalisation.
The emirate controls about 10% of the world's proven oil reserves and is a key US ally in the region.