The Maples Ward on the site houses a 10 en suite single-bedroom unit to provide a specialist environment for adults with severe mental illness.
The new-look unit has been equipped with two new art rooms where patients can be supported by staff in safe surroundings.
The renovation includes a quiet area to support patients in their recovery and a larger lounge for patients to relax and socialise.
Maples features two lounge spaces, a separate lounge for female patients, a clinic room, treatment room, family room, kitchen, dining room and activity room.
The design of the building has focused on ensuring it is a safe and comfortable environment with rounded edges to prevent patient harm.
Mark Young, associate director of estates transformation at Solent NHS Trust, said: ‘This has been a major investment in our mental health facilities for people in the area.
‘The modernised accommodation will make a real difference to patients needing care at a difficult point in their lives.’
Soft shades have been used to support relaxation and create a feeling of calm.
A new outdoor multi-use games area has been installed which provides a place for patients to exercising outdoors as part of their road to recovery.
The all-weather pitch was funded through a £50k donation from NHS Charities Together, with money raised in part by captain Sir Tom Moore in support of NHS staff, volunteers and patients during the pandemic.