The Liberal Democrat conference in September 2012 is expected to inject £10m into the local area and will see 8,000 delegates visit the city.
The conference was last held in Brighton in 2007, although the city hosted the Labour Party conference in 2009 and the Conservative spring forum earlier this year.
Visit Brighton convention bureau sales manager Darren Johnson said: "To once again be selected to host a high profile conference such as this further highlights our city’s credentials as a destination which can deliver exceptional city-wide business events."
The conference will be held at the newly refurbished Brighton Centre which has undergone a £1m refurbishment, which included an upgrade to the existing breakout areas, the conference centre’s Skyline restaurant, and new signage.
The Lib Dem conference is in Liverpool this year, and will be held in Birmingham in 2011.