Kuwait's parliament has unanimously approved the appointment of Sheikh Nawaf al-Ahmad as crown prince.
The succession breaks with a ruling family tradition of sharing power
Sheikh Nawaf, in his late 60s, is a brother of the recently installed emir, and a former interior minister.
His confirmation completes the transition to a new leadership after the death in January of Sheikh Jaber al-Ahmad, who ruled for 28 years.
Sheikh Jaber's designated successor was removed by parliament on health grounds and replaced by the sheikh's brother.
In another ceremony in parliament on Monday, the new government was sworn in.
The new prime minister, Sheikh Nasser Muhammad al-Ahmad, said his administration would follow the reform programme of the previous government.
Sheikh Nasser is a nephew of the new emir, Sheikh Sabah al-Ahmad, whose accession came after an unprecedented leadership crisis last month.
The ailing emir, Sheikh Saad al-Abdullah, was replaced after only 10 days through a vote in parliament, apparently against his will.
Sheikh Sabah's succession arrangements break with a long-held tradition of alternating power between rival branches of the Sabah dynasty.
Kuwait controls about 10% of the world's proven oil reserves and is a key US ally in the region.