|The Downs near Patcham|
The council said it had owned land around the city, in Ditchling Road, Old Patcham Court Farm and Plumpton, for many years.
However, there has been limited access for visitors.
The Green-led administration said it had negotiated public access with farmers who currently have tenancies on the land.
Councillor Pete West said: "Downland is a wonderful resource and now these areas owned by the city will be open in perpetuity to walkers, sightseers, birdwatchers, runners, and others looking to enjoy it."