The Lucy Tower multistorey car park on Brayford Pool in Lincoln will be closed for more than four months for major structure works.
The £1.1 million works will begin on March 25 and are expected to last around 20 weeks, with a reopening date some time in August.
Lucy Tower has 458 spaces and is used on average by 350 motorists per day.
Engineers will replace the steel supports at the lower levels of the 30-year-old car park, after the upper levels were repaired in 2011 and 2012.
The works are expected to extend the life of the car park by 20 years. Lucy Tower brings more than £850,000 per year in revenue for the council.
The City of Lincoln Council has made alternative arrangements to divert drivers at alternative car parks on Tentercroft Street and Broadgate multistorey.
In order to be able to absorb the number of Lucy Tower car park users, the council is also moving its staff from their allocated spaces at City Hall.
City Hall will have some 115 spaces available as Pay and Display on Orchard Street throughout the week, while the County Council is extending its 130 spaces to the public at weekends only, between 8am and midnight.
New signage will be installed to divert users from Lucy Tower, and leaflets will be handed out ahead of the car park closure.
The Lucy Tower closure is timed to coincide with the reopening of the Thornbridge multistorey next to the bus station, after £400,000 resurfacing works.
From April new parking fees will come in force, which means all-day parking for £2.50 will be available at car parks at County Council offices, Broadgate, Sessions House (Lincoln College) and Rosemary Lane.
The works are part of planned maintenance at all three multistoreys in the city, Angela Andrews, Director of Resources at the City Council explained.
The Broadgate multistorey will also undergo repairs some time in 2014 or 2015.
Steve Bird, Assistant Director of Communities and Street Scene at the City Council, said: “We are aware this closure will affect a lot of people, but these works are vital to ensure Lucy Tower is able to stay open for the longer term.
“We recognise the loss of so many spaces is important for businesses, so we are doing all we possibly can to mitigate this loss, including opening up the adjacent staff car park at City Hall.”
City Council Leader Ric Metcalfe added: “We need to do this work, but it’s never a good time to do it.”