The investment see the installation of two top-of-the-range mobile cranes and the refurbishment of its cool store and chilled produce processing area, with work starting in the next couple of months.
This latest investment will allow it to undertake a much faster, more energy-efficient operation at its cargo-handling terminal.
Alastair Welch, port director at ABP Southampton, said: "This latest £8.3m investment to improve port facilities will ensure we develop our capabilities to meet the increasing demands of the Fresh Produce Terminal into the future.
"The proposals to install new, more efficient harbour cranes and improved temperature controlled warehouse facilities together with the use of new energy efficient lighting and chilling technology will greatly enhance our customer offer."
The work is due to commence shortly with most of the refrigerated areas completed by the end of October and the remaining work by February 2017.
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