Sultan Ibrahim ibni Sultan Iskandar, 65, assumed the role of Malaysia's new king on Wednesday.
Ibrahim succeeds Al-Sultan Abdullah Ri'ayatuddin Al-Mustafa Billah Shah whose five-year term came to an end on Tuesday.
He was sworn-in as the 17th king, locally called Agong, at Istana Negara, the official residence of the king, in capital Kuala Lumpur.
Earlier, the new king served as Sultan of Johor state in southern Malaysia.
He was elected by Malaysia's royal family last October.
Malaysia's royal family has nine rulers who take the top position in turns, according to a system agreed to in 1957 when Malaya secured independence from British rule.
Malaysian Prime Minister Anwar Ibrahim greeted the new king and said the people "will continue to give undivided obedience and loyalty" to the royal rulers.
Sultan Nazrin Shah, 67, of northwestern Perak state took oath as the deputy king.
