The summer spectacular will take place over the last weekend of July.
East 17 were the first headliner revealed by the organisers, being the leading act on Saturday, July 30.
The group were one of the most popular boy bands in the 1990s, as they had 12 top 10 singles between 1992 and 1998.
Classic songs such as House Of Love and Its All Right contributed to East 17 selling over 18 million albums worldwide.
The band is also known for their 1994 hit Stay Another Day, which was a Christmas number one that year.
Gareth would later be signed by Simon Cowell to his BMG label.
Since then, he has sold 3.5 million records in the UK.
Too Much 2 Tone are set to kick off the first night, July 29, as the headliner, and the winners of the Battle of the Bands music contest are also planned to perform.
Gosport Waterfront Festival will take place at Walpole Park.
Early bird tickets cost start at £3.74 and VIP packages are £63.59.
These are on sale now, and can be purchased here.
More information about the other acts can be found on the Gosport Waterfront Festival website.