The consortium, led by France’s Alstom Conglomerate and also including Spain’s Acciona and Turkey’s Gulermak, will construct a 15 kilometre (nine mile) extension to the site of the fair, a statement said.
Alstom will supply 50 trains, 15 of them for the new extension and 35 to upgrade existing services, the statement said.
Ten international consortiums bid for the project, it added.
The consortium, dubbed Expolink, will begin work on the project in the final quarter of 2016, Road and Transport Authority chairman Mattar al-Tayer told a press briefing.
Services should begin on May 20, 2020, five months ahead of the trade fair, he said.
Alstom had led a consortium that built Dubai’s 10-kilometre (six mile) tramway, which cost just over one billion dollars and opened in 2014.
The Dubai Metro, which transformed transportation in the Gulf city state when it opened in September 2009, was built by a consortium led by Japan’s Mitsubishi.
Mitsubishi was competing with the Alstom-led consortium for the new extension, sources familiar with the tenders said.
Alstom chief Henri Poupart-Lafarge said the consortium is “proud to have been chosen,” describing the contract as a “new major award for Alstom in the UAE”.
“We will bring the most innovative and cutting-edge technologies to Route 2020 project and continue to be reliable partners of RTA,” he told reporters.
The metro was projected to cost $4.4 billion when work began in 2004, but that had surged to $7.6 billion by the time it was completed.
The Dubai Metro has two lines, a 52 kilometre (32 mile) Red Line and a 23 kilometre (14 mile) Green Line.
The city state has a population of 2.5 million people, most of them expatriates, and received more than 14 million tourists last year.
Its target is to receive 20 million visitors a year by 2020.