The confirmation comes after HS2 won a legal appeal to lift a suspension order on the contract award.
Rival bidder Bechtel launched a legal challenge against the procurement process which is due to be heard next year.
HS2 has now been allowed to award the deal to the winning JV in the meantime while the whole project is also under review by the Government.
The joint venture will be responsible for the final design, construction and commissioning of Old Oak Common station in North West London, delivering six underground platforms as well as up to eight platforms on the adjacent Great Western Main Line.
Nigel Russell, Project Director for the Balfour Beatty Vinci Systra joint venture said: “This award reflects the combined strength of our joint venture and recognises our world-class capabilities in designing, managing and delivering complex infrastructure projects.
“We look forward to applying our expertise to deliver this critical piece of national infrastructure so essential to driving the skills agenda, to the rebalancing of the UK economy and to the enabling of a resilient and competitive construction and infrastructure industry.”
At construction peak the project will employ a direct management team of 140 and a wider workforce of approximately 2,500.