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 UN panel will now try to determine if the Syrian government was responsible, as the US has alleged.
The attack on Khan Sheikhoun in Idlib province was the most deadly in Syria in more than three years.
It prompted a retaliatory US missile strike against a Syrian air base.
The fact-finding mission for the Organisation for the Prohibition of Chemical Weapons (OPCW), which is based in The Hague, concluded that, after interviewing witnesses and examining samples, "a large number of people, some of whom died, were exposed to Sarin or a Sarin-like substance".
"It is the conclusion of the FFM (fact-finding mission) that such a release can only be determined as the use of Sarin, as a chemical weapon," a summary said.
The new report has been circulated among OPCW members but has not been made public.
A joint UN and OPCW investigation will now investigate who was to blame for the attack.
US President Donald Trump ordered a cruise missile strike on Shayrat air base after US officials concluded that the facility was where a Syrian Air Force jet had been armed with a Sarin-filled bomb.
Syrian President Bashar al-Assad has previously said that the incident was fabricated.
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.
[NEXT_CONCEPT]
A fact-finding mission by chemical weapons watchdog the OPCW has concluded that the banned nerve agent Sarin was used in an attack in northern Syria in April that killed dozens of people.