Sheikh Khalid bin Sultan Al Qasimi, 39, was the owner of a British fashion label, Qasimi, which has been in business since 2008.
Three days of mourning have been declared in the emirate and flags have been ordered to fly at half mast.
In a statement about Khalid Al Qasimi, government of Sharjah said: “The Ruler’s Court expressed its deepest condolences to His Highness the Ruler of Sharjah, family of the deceased and members of Al Qasimi family, praying to Allah the Almighty to rest his soul in Paradise.”