Chief executive John Wigglesworth said since 1994 each stage of the upgrade had been funded entirely by the community through the Hokianga Health Enterprise Trust with help from sponsors.
"We thank the late Sheila Wilson for her generous bequest, Hokianga Hospital Auxiliary for their relentless support and our sponsorship partner Comvita's Kiwi Bee apiary business," Wigglesworth said.
Other guests at Friday's celebration included Far North Mayor John Carter, Northland District Health Board chairwoman Sally Macauley and Comvita general manager apiaries Trevor Clarke.
The trust has a three-year sponsorship agreement with Kiwi Bee Medical, the apiary arm of mānuka honey exporter Comvita. Kiwi Bee funding has so far been used to improve the emergency department, build a new X-ray room and upgrade some wards.
As well as overseeing Hokianga Hospital, Hokianga Health Enterprise Trust has 10 general practice clinics throughout North and South Hokianga providing healthcare with no charge. The trust also runs a maternity service and healthy living programmes.