The $1.5bn Burj Dubai was dramatically renamed Burj Khalifa on Monday night during a spectacular ceremony to open the world's tallest tower.
The announcement was made in front of the thousands of people who had squeezed into the Downtown area to witness one of the world's biggest firework displays.
Dubai's ruler Sheikh Mohammed bin Rashid al-Maktoum renamed the tower after the president of the UAE and the ruler of the neighbouring emirate of Abu Dhabi.
The opening coincided with the fourth anniversary of the accession of Sheikh Mohammed to power in the emirate of Dubai.
Earlier, Emaar Properties said on Monday the final cost of the world's tallest tower stood at $1.5 billion, with 90 percent of the building already sold, and that it would benefit 2010 results.
Chairman Mohamed Alabbar said the Burj Dubai opening would have a positive impact on the first three quarters of 2010.
Started at the height of the economic boom and built by some 12,000 labourers, the world's tallest building opens on Monday in Dubai as the once-booming emirate seeks to revive optimism during its financial crisis.
Emaar Properties also said it will focus on international projects where it was already present, adding that the emirate's property prices have stabilised.