The Port of Southampton is one of the UK’s largest ports for exports with £40bn worth of British manufactured goods passing through each year.
Southampton is also the country’s number one for vehicle handling, with more than 900,000 vehicles passing through in 2015, including around 520,000 for export.
The first £25m tranche of the investment will deliver two new vehicle handling facilities, together capable of storing 7,600 vehicles on route from UK factories to global markets.
The new facilities will support a range of UK vehicle manufacturers, including Jaguar Land Rover.
ABP chief executive James Cooper said: "Southampton is the UK’s number one port for exports, handling exports worth some £40bn, and it is the UK’s number one for vehicle exports.
"The port is a critical part of the supply chain for the British automotive industry, providing essential access to global markets.
"Our investment will build on this critical role and support our customers’ drive to continue to grow their exports well into the future."
The second phase of investment will see a further two facilities built. Ultimately, the investment will add a further 15,000 spaces to the port’s capacity and take the total number of vehicle handling facilities in Southampton to nine, capable of carrying 55,000 vehicles.
International trade secretary Liam Fox added: "This investment is positive news not just for Southampton, but for our world-class automotive industry as a whole.
"Southampton is a key route for British brands to access international markets and this investment will allow exporters to take advantage of the global demand for British-made vehicles.
"Last week, ONS statistics revealed UK car exports reached a record high in July and investments like this will help to strengthen exports in the sector and will be a further boost for confidence and optimism."