The expansive refuse siteÂ to the west of the M275, will be given a gleaming makeover to create the Horsea Island Country Park.
It is hoped the new country parkÂ will be open to the public in 2020.
The news has been welcomed by Portsmouth North MP Penny Mordaunt.
She said: '˜This is great for the city's green credentials. Literally turning an old landfill site into what will eventually become a beautiful country park should be something that we can all get behind and enjoy when it opens to the public in 2020.Â
'˜It's important that the city continues to see sensitive developments such as Horsea Island Country Park and is a testimony to what can be achieved under difficult circumstances such as turning an artificially made landfill site into open green space.
'˜The new park could be a new jewel in the crown of the city and I welcome this news.'
Councillor Donna Jones, the city's Tory leader and former council boss, said the park would be a major new attraction, boosting tourism and economy in the future.
She added a new bridge might even be created from the M275 which will allow cyclists and pedestrians to stroll to the county park from the city.
Cllr Jones added: '˜This will be yet another feather in the cap of Portsmouth.
'˜This is going to be a real good way to bring people into the city.
'˜When people come into our beautiful city, to have this spectacular country park welcoming them will be fantastic.'