Sheikh Hamdan bin Rashid, Deputy Ruler of Dubai and Minister of Finance, died on Wednesday.
His brother, Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, announced Sheikh Hamdan's death.
A mourning period of 10 days was declared in Dubai.
Flags will fly at half-staff in Dubai and work will be suspended in government departments and institutions for three days, starting on Thursday.
Other attractions such as Expo 2020's sustainability pavilion will close and dates for reopening will be announced soon.
Sheikh Mohammed bin Rashid led funeral prayers at Zabeel Mosque on Wednesday.
He was joined by Sheikh Hamdan bin Mohammed, Crown Prince of Dubai, and other sheikhs.
They were restricted to family members because of Covid-19 restrictions.
Sheikh Hamdan, who was in his seventies, had been unwell for some months – Sheikh Mohammed tweeted prayers and well-wishes for his brother as recently as March 9.
On Wednesday, Sheikh Mohammed posted a picture of his brother saying: "We belong to God and to Him we shall return ... May God have mercy on you, my brother, my support and my companion."
Sheikh Hamdan bin Rashid, Deputy Ruler of Dubai, dies
Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the Armed Forces, paid tributes to Sheikh Hamdan.
"Today, we lost one of the loyal men of the Emirates after a life full of giving and sincere patriotism," Sheikh Mohamed tweeted.
“May God have mercy on my brother Sheikh Hamdan bin Rashid, and reward him with the best reward for what he offered to his country and its people.
“I express my condolences to my brother Mohammed bin Rashid and the honourable Maktoum family for this great misfortune. [I wish them] patience and solace.”
Sheikh Dr Sultan bin Muhammad Al Qasimi, Ruler of Sharjah, mourned the death of Sheikh Hamdan.
The Ruler of Ras Al Khaimah, Sheikh Saud bin Saqr Al Qasimi, said the UAE has lost today one of its loyal and devoted leaders.
“God have mercy on Sheikh Hamdan bin Rashid Al Maktoum. With his wisdom and insightful vision, he helped build our institutions of government since the founding days of this nation.
“He helped lead a march of national achievements and humanitarian work that will go down in the history of the nation and the conscience of the Emirati people.
“Our condolences to His Highness Sheikh Mohammed bin Rashid Al Maktoum, to the honourable Al Maktoum family and to the people of the Emirates for this great loss to the homeland.”
Sheikh Humaid bin Rashid Al Nuaimi, Ruler of Ajman, and Sheikh Saud bin Rashid Al Mualla, Ruler of Umm Al Quwain, expressed their heartfelt condolences on the death.
Sheikh Hamdan bin Mohammed, Crown Prince of Dubai, paid tribute to his uncle.
“To Allah we belong and to Him we shall return,” he said.
“Today, the country bid farewell to one of its symbols and a knight who stepped down after a journey of giving.
“His journey will remain immortal and from it we will draw inspiring moral lessons in upholding the status of the homeland and in spreading the roots of goodness.
“We ask God Almighty to have mercy on Sheikh Hamdan bin Rashid Al Maktoum and make heaven his resting place.”
In October, Sheikh Hamdan was wished well by officials and colleagues after surgery abroad.
They welcomed him on his return to the Emirates after the operation.
Details of the surgery or the location were not stated.
