STORY: On Friday, the Ministry of Presidential Affairs announced the death of Khalifa, who was also the ruler of the UAE's richest emirate, Abu Dhabi, but gave no details.
Khalifa, born in 1948, had rarely been seen in public since suffering a stroke in 2014.
He was buried wrapped in a UAE flag at the Al Bateen cemetery after officials and family members held prayers.
Under the constitution, vice-president and premier Sheikh Mohammed bin Rashid al-Maktoum, ruler of Dubai, would act as president until the federal supreme council which groups the rulers of the seven emirates meets within 30 days to elect a new president.
Khalifa's death comes at a time when Abu Dhabi's ties with Washington have been visibly strained over perceived U.S. disengagement from its Gulf allies' security concerns.
The UAE announced a 40-day mourning period with flags flown at half-staff and suspended work at all public and private sector organizations for three days.