The 74-metre (240 ft) roll-on roll-off ship will operate on Southampton-East Cowes route.
According to ferry operator Red Funnel, a dedicated freight service was needed as it had "run out of capacity" on the existing vehicle ferries.
The order marked the latest investment by the consortium of UK & Canadian pension funds that bought Red Funnel last year.
Currently, the operator carries more than half the commercial freight traffic on/off the island.
The new vessel would free-up space on the 2 existing vehicle ferries.
Cammell Laird yard is due to deliver the new ferry in spring 2019.