Earlier on Saturday, Kuwait's state TV suspended its regular programming and broadcast Quranic verses, a sign of mourning in the Islamic tradition.
He had been in power since September 2020, following the death of his half-brother, Sheikh Sabah al-Ahmad al-Jaber al-Sabah, who was 91.
Sheikh Nawaf had a long and distinguished career in public service before becoming the ruler of the oil-rich Persian Gulf state. He served as defence minister during the Iraqi invasion in 1990.
He was appointed as the crown prince in 2006, and was popular among the ruling al-Sabah family for his modesty and low profile.
His reign was marked by political stability and continuity, as he sought to maintain Kuwait's welfare system and foreign policy. However, he also faced economic challenges, as the country's debt crisis and low oil prices limited its fiscal capacity.
Kuwait, which has the world's sixth-largest known oil reserves, has a population of about 4.2 million people.
Source: Agencies