Newark and Sherwood District Council plan to restore Newark's Magnus buildings into a museum about the 17th Century war.
The project will cost £5.4m in total and will open in September 2014.
The centre could attract more than 60,000 visitors each year, according to the authority.
Councillor Roger Jackson, the district council's cabinet member for leisure and culture, said: "The new museum will provide a hub for tourism, directing visitors to attractions across the district and Nottinghamshire."
Newark and Sherwood District Council said it has applied to other grant-funding bodies to make up the rest of the money needed.
The authority has worked with the Heritage Lottery Fund to put together plans to renovate the Magnus buildings, part of which date to 1529.
The Royalists surrendered Newark following a siege in 1646 towards the end of the civil war, which resulted in the defeat of King Charles I by the Parliamentarians.
In addition to Civil War displays, exhibition galleries will focus on the local history of the towns and villages of Nottinghamshire.
The Newark Torc, an Iron Age necklace found using a metal detector near the town, will also be displayed in the centre.
It will be the first time the item will be displayed in the district after being loaned to the British Museum.

Liberal Democrat AM Eluned Parrott said the Welsh government had "wasted" more than £52,000 on them at railway stations in south Wales.
She accused ministers of spending public money to "promote themselves before an election".
The Welsh government said it was unapologetic about the campaign.
A spokesman said: "We are not going to apologise for informing the Welsh public about one of the most important economic and social projects in Wales' history.
"Are the Liberal Democrats really saying that we should not be providing people in Wales with this important information?"
Ms Parrott said her party backed the project, but added: "To all intents and purposes, here we have Labour ministers spending over £50,000 of public money to promote themselves before an election.
"This is money spent only on marketing the fact that one day, years in the future, there will be a Metro in south Wales.
"This is a cynical way of spending public money. The minister is wasting tens of thousands of pounds on a useless poster campaign."
Work on the Metro is set to start in 2017 and finish in 2020, a government spokesman said.
Formal consultation for the £600m programme to develop an integrated network of rail, bus and light rail services begins in 2016.
Buildings in a Nottinghamshire town are set to become a National Civil War Centre after a £3.5m grant from the Heritage Lottery Fund was secured.
[NEXT_CONCEPT]
An advertising campaign promoting the South Wales Metro has been criticised as "useless" and a "cynical way of spending public money".