The firm will deliver the massive interchange scheme to build a transport hub for the city along within a major commercial building.
Work could starting next spring, subject to planners approving the scheme which is due to be submitted shortly.
A Foster + Partners designed project, the 450,000 sq ft building complex will incorporate a new city bus station, linking it to the railway station.
At its highest point, it will offer 11 storeys for private residential apartments and a hotel and will then descend down to seven storeys as it moves closer to the grade listed train station.
The contract award follow a separate deal with ISG last month to deliver a new headquarters for BBC Wales at the Cardiff Central scheme under an £80m contract.
Before that Willmott Dixon secured the first office building at the site which is close to completion.
Cardiff Central is being developed by local firm Rightacre in partnership with Legal & General which recently committed to investing £400m in the ambitious plan.