Coffee can be served from the former public lavatories next to the River Uck in the centre of Uckfield.
Planning permission for the change of use has been given by Wealden District Council.
It is intended the premises will be used as a coffee/takeaway bar, also serving snacks made on the premises.
Opening hours would be from 6.45am to 6pm, Monday to Friday; 6.45am to 4pm on a Saturday and 8am to 4pm on a Sunday and bank holiday.
Existing entrances to the building will be bricked up to form new windows. The shopfront will face River Way.
A report from Wealden planning department said the lack of parking was no reason to refuse planning permission.
There were, they said, nearby car parks and the business proposed was similar to others in the High Street.