Sheikh Khaled bin Mohammed bin Zayed Al Nahyan, the UAE leader's eldest son, is now the oil-rich Middle Eastern country's crown prince, effectively next in line for its leadership.
Sheikh Tahnoon was already named chair of the $790 billion Abu Dhabi Investment Authority, the emirate's main sovereign wealth fund, earlier in March.
Sheikh Mohammed bin Zayed Al Nahyan, Crown Prince of the Emirate of Abu Dhabi.
He described the decision as "formalizing the leverage Abu Dhabi has over Dubai, and how little Dubai will be allowed to say in foreign policy."
Prime Minister and Vice-President of the United Arab Emirates and ruler of Dubai Sheikh Mohammed bin Rashid al-Maktoum attends the Global Women's Forum in Dubai, United Arab Emirates, February 16, 2020.