The 5939 square metre rectangle block is leased to six tenants from the medical industry including industry giant Healthscope which has a lease in place until 2018.
Colliers International director Peter Bremner, who marketed the property with colleague Pat Burke, said the new owners will consider rebuilding the site as a residential complex in the future.
Acknowledging the funding pressures which have prevented many possible sales from proceeding this year, Mr Bremner said the Prahran campaign highlighted that well located inner-city investments are still supported by purchasers and their banks.
Australian Unity listed the Prahran property for sale in late July.
In March, another AU division listed for sale three industrial assets valued at about $11.5 million.
Last December AU reaped $10 million selling the prominent St Kilda Road office building formerly occupied by Austereo radio stations Fox FM and Triple M.