A parcel delivery firm wants to open a depot on the outskirts of Swansea which it says would create 130 jobs.
DPD would be the first tenant at Parc Felindre, on the site of a tinplate works which closed in 1989.
Swansea council leader Rob Stewart said the plan showed confidence in the city.
Plaid Cymru assembly member Dai Lloyd has criticised the delay in attracting business to the site, which has had £36m of Welsh Government, European and council money spent on it.
Swansea council officers are working through DPD's planning application for a "high-quality" office and warehouse building, open 24 hours a day.
The new base would take up eight acres (3.2ha) of land, about a quarter of the size of the Amazon warehouse in neighbouring Neath Port Talbot.
The site had been earmarked for a private hospital, but the project did not materialise, according to the Local Democracy Reporting Service.
The tinplate works, which used to employ more than 2,000 people, closed in 1989 before being demolished in 1996.
Swansea's former Liberal Democrat-led administration agreed a strategy for the business park in 2006, which envisaged high-tech and emerging industries setting up there.
When it emerged in June that £36m had been spent on the site so far, Dr Lloyd said there had been "a lot of frustration" about the lack of progress in attracting businesses there.
The Welsh Government said developing such sites was "challenging", while Mr Stewart said that despite criticism the Labour-led council had "continued to focus on securing investment, tenants and creating jobs".
He added that further investment announcements would be made in "the coming weeks and months".