It would make the disused Fawley power station chimney the tallest such attraction south of London's Shard.
Developers Fawley Waterside said it would be the centrepiece of a "merchant city" development.
The power station closed in 2013 after more than 40 years in operation.
Architects plans show a petal-shaped glass structure at the centre of a Â£1bn development featuring a marina, housing and restaurants.
It also includes fast ferry links to Southampton and Portsmouth.
With an application for outline planning permission due later this year, building could start in 2018.
The oil-fired Fawley Power Station, on the western side of Southampton Water, was commissioned in 1971 and was capable of powering one million homes.
The 300-acre site was sold to Fawley Waterside developers in 2016.
Aldred Drummond of the company said: "We'd be mad to knock the chimney down - its our signature piece of infrastructure.
"If you think of the money spent building the i360 in Brighton, or the Spinnaker Tower in Portsmouth, this building is already there so with relatively little investment we can do something very spectacular."
1971
Commissioned on the western shore of Southampton Water
2,000 megawatt oil-fired power station fuelled by nearby Esso refinery
198 metre-high chimney dominates the Solent sykline
1,100  miles of cable were laid within the power station
One million homes were powered by Fawley
A 650ft (198m) power station chimney could be converted into a public viewing tower and restaurant overlooking the Hampshire coast, under plans released by developers.