The contract, for the section between Bobigny-Pablo Picasso and Champigny Centre stations, is valued at €2.54bn (£2.19bn).
Grand Paris Express is a new network of rapid transit lines under construction in the Ile-de-France region comprising four new lines for the Paris Metro plus extensions of the existing Lines 11 and 14.
The new contract is for 17km of tunnel, 15 major rail structures and two entrance structure, laying of railway track, high- and low-voltage electrical systems and associated mechanical and electrical installations.
The consortium will also build six new stations at Bobigny-Pablo Picasso, Pont de Brody, Bondy, Rosny Bois-Perrier, Val de Fontenay and Nogent-Le Perreux.
The consortium includes eight architectural firms: Architecturestudio, Ar.Theme Associes, FBCC, LA/BA, Viguier, Wilmotte & Associes and BIG-Silvio D’Ascia Architecture consortium.
Eiffage will also lead development works at the existing Champigny Centre station for Line 15 East as well as construction of an operations centre at Rosny-sous-Bois.