An extra 1290 m2 of exhibition space will be built at the international centre, which regularly hosts political party conferences.
A 200-seat auditorium along with community arts facilities will also be part of the pavilion's refurbishment.
The overall scheme is valued at £23m. Some of the money for the project will come from the sale of council land, which has raised £9m. The South West Regional Development Agency is also expected to provide funds.
Stephen Godsall, the council's director of leisure and tourism, said the scheme will be put out to tender early next year.
Leader of the council Bob Chapman added: "The scheme will provide a welcome injection to the business tourism sector and the economy of the town, helping us to become a world class resort."
The council first put in a bid for PFI funding to the Department for Culture, Media and Sport last year when it asked for £40m to redevelop the pier and other parts of the town. This proposal was rejected as too ambitious and the council was asked to come back with another scheme.