The restored old dairy building facade in Castle St was unveiled yesterday, after work began in August.
The design was based on the 1930s Cadbury Fry Hudson era, when the building was the company’s headquarters.
Mondelez Dunedin engineering manager Marty McArthur said it was the "last official act" of the company before it handed over the factory site to the Crown on Thursday.
The company announced plans to close the factory in March last year and in May this year the Ministry of Health revealed the site would be part of the new Dunedin Hospital.
"We had intentions before we were closing to do the facade, but I guess once the site was sold, Mondelez decided to leave a lasting legacy to the city."There has been 150 years of manufacturing on the site."
The building was earthquake-strengthened and heritage features stripped from the building in the 1950s were restored.
The project took up to a year of planning and included Dunedin architects, engineers and fibrous plasterers.
They sourced old blueprints and the result was "very much what it would have looked like", Mr McArthur said.
Dunedin city councillor David Benson-Pope said at the unveiling while the loss of chocolate manufacturing was "regrettable" it was now a matter of history.
The project was well served by being led by locals, and preserved the history of the "best historic precinct in the country".
Although there was no certainty with the hospital rebuild, he was "confident" the facade, and possibly the entire building, could be retained.
The building has been the site of whisky distilling and beer brewing.
The Hudson family bought the building in 1900 to use as a biscuit factory and merged with Cadbury in 1930.
