Brighton and Hove Hebrew Congregation's board has approved the start of work next month on the first phase of essential repairs to the historic Middle Street Synagogue.
The cost of making the building safe, wind and waterproof is in excess of £360,000.
English Heritage has contributed £317,000 towards the project and the shortfall has been covered by internal fundraising.
"We are going to restore this building as a cultural, educational and historical centre," pledged the Brighton and Hove chairman, Martyn Cooperman.
Stage two of the project will be the redecoration of the building, which was consecrated in 1875.