Hove Town Hall will host officers and other staff from Sussex Police from Thursday 14 February.
Only back office policing staff will remain at the old police station in Holland Road, Hove, until it is sold.
The site is expected to be used for much-needed school places by Brighton and Hove City Council subject to a deal being agreed with Police and Crime Commissioner Katy Bourne.
The police office at Hove Town Hall, in Norton Road, will house neighbourhood police. The force said that the public would be able to report incidents and stolen property there as well as ask for crime prevention advice and view online services.
Sussex Police said that the move reflected the situation that existed until the police station in Holland Road opened in 1964.
Before then, from 1882, the police had offices and cells at the old Hove Town Hall which also housed the local court.
Chief Superintendent Graham Bartlett, the Brighton and Hove divisional commander, said: “Local people told us they want to see more of their neighbourhood policing team out in their area and to be able to talk to them in a convenient location.
“Working together means people can expect a better service, as police will be working jointly with partners to identify and tackle any problems.
“Together, the partner agencies get a fuller picture of what is happening and can draw on different expertise to help the community.
“We know that the way that people want to access our service is changing.
“As well as being able to talk to officers at local street surgeries and in community meetings you can now also ask our officers a question using social media such as Twitter or Facebook.
“In addition, the new Sussex Police Online Help Centre contains over 500 FAQs (frequently asked questions) and also the facility to chat online with a member of our call centre staff.
“These are all major developments in making our people as accessible as possible.
“In the past month alone, over 114,000 people have logged on to our website to find out more about the service we provide.
“Across the city in recent years our neighbourhood policing service has developed significantly to respond to the needs of different parts of the community, including introducing a dedicated Street Community Team and LGBT Team.
“We are also working more closely than ever with our partners to provide a truly joined up service through the Safe in the City community safety partnership.
“Each and every area in the city has a dedicated policing team working hard on priorities set by local people through the network of local action teams.
“From tackling anti-social behaviour to targeting speeding drivers, it’s imperative that the teams are as accessible as possible to our communities.
“Policing isn’t about buildings. It’s about people. And fundamentally this move is about equipping the teams with the right tools to get back into the heart of the local community.
“It is vital that we keep pace with the changes happening around us and ensure our service reflects the needs of local people.”
The announcement came on the day that Home Office figures showed that Sussex Police had 126 fewer officers at the end of last September compared with the same time the year before.
The 4.2 per cent drop means that the force had 2,896 full-time equivalent officers last September down from 3,022.
