Hampshire Chamber of Commerce has thrown its support behind the £12m scheme, which aims to prevent HGVs from having to park in public roads.
One of the firms based near the docks has also expressed support for the "long overdue" scheme.
The company wants to provide better facilities for HGV drivers as well as eliminating the need for lorries to use surrounding roads.
In a letter to the city council the Chamber of Commerce says: "The port plays a significant part in the city and the region. Its economic development and growth is essential.
"This provision will assist to reduce parking elsewhere in the city and ensure a suitable alternative within the Western Docks is available."
Its letter says: "We welcome plans for a long overdue HGV parking facility in the city, which is one of the busiest container ports in the UK.
"Thousands of trucks come into Southampton but there's no parking apart from the services on the M27, which are outside the city and not secure.
"When truckers are delayed at the port they often run out of driving hours, leaving them with only industrial estates or residential streets to park in - with no welfare facilities available."
The City of Southampton Society is also supporting the application.
It says the scheme will reduce the number of commercial vehicles parking in side streets as well as providing drivers with welfare facilities such as showers and a cafe/restaurant.
ABP's application says: "When the terminal experiences delays or unexpected issues the current pre-gate area quickly becomes full and it becomes necessary for HGVs to be turned away.
"As a result, HGVs end up parking on the public highway network, which generates a number of safety and social issues.
"The truck park will reduce the number of port-related lorries queuing and parking on local roads as well as improving the welfare of drivers by providing services which are currently not available within the port."