The Gunwharf Quays attraction is offering 25 per cent off to all addresses that start with PO.
The limited offer is for two weeks only from this Monday andÂ ends on September 2.
With the discount, standard ticket prices will be reduced to Â£8.25 for adults, Â£6.38 for children and Â£7.50 for students and seniors. A family ticket for twoÂ adults and twoÂ children will cost just Â£25.50.
The tower offers a year-round discount to residents of Portsmouth and Gosport but this offer includes addresses in Fareham, Havant, Chichester, Bognor Regis andÂ the Isle of Wight.
Tony Sammut, general manager, said: '˜We are delighted to extend this discount to residents across the region. There's so much for all ages to enjoy at theÂ Spinnaker Tower.'
Discounted ticketsÂ cannot be purchased in advanceÂ online and a valid proof ofÂ address is needed.