The new block will include an accessible "Changing Places" bathroom and two public toilets.
The Dunedin City Council project is expected to cost about $750,000.
The Changing Places bathroom is a first for the South Island.
It will be designed for people with complex care needs who are unable to use standard accessible bathrooms or public toilets.
Key features include a height adjustable toilet and hand basin, privacy screen, built-in hand support grab handles, a change table that doubles as a shower bed as well as a ceiling track hoist.
The old toilets have been decommissioned while the new facilities are being built. Public restrooms are available nearby at the Dunedin Railway Station, Toitū Otago Settlers Museum, Queens Gardens and at the central city bus hub.
