The contract, which is worth US$3 billion, was signed at the royal palace of Bahrain in the presence of Vinci's head Yves-Thibault de Silguy.
The Qatar-Bahrain Causeway, as it has been named, will reduce the time of travel between the two states from the present five hours, via Saudi Arabia, to about 30 minutes.
Construction on the bridge will begin after nine months of studies on the project have been carried out. Some 12,000 vehicles will be able to travel daily between Bahrain and Qatar when it is completed.
Currently, the world's longest fixed bridge is the Lake Pontchartrain Causeway, which spans 38.4 kilometers.
