Anthony Tedeschi, who curates rare books at the Dunedin City Library, was asked to authenticate the bible, found at the bottom of a box in a church cupboard.
He believed it was the only 1616 King James Bible in the southern hemisphere, and one of only a few left in the world.
In a blog about the bible, Mr Tedeschi said it was the 31st copy of the 1616 folio edition recorded, and the only one recorded in Australasia.
Research showed the book was bequeathed to the Palmerston North church by a member of the congregation in 1912.
"That member, Thomas Pattinson, emigrated from England to New Zealand sometime between 1874 and 1881.
"Though provenance research is ongoing, it appears Pattinson's lineage stretches back to another Thomas Pattinson born in Scotland around 1615.
"It could very well be that the 1616 KJB had been in the family from the time of its printing," Mr Tedeschi said.
The bible has been restored and will be dedicated at a special church service before being put on permanent display.
Staff at the Dunedin City Library said special books were becoming more of a rarity as the size of people's collections diminished in the modern age.
Fewer people could afford large personal collections, or they used modern means to appreciate literature.
Dunedin's central library housed two rare-book collections, totalling many thousands of items.
The McNab New Zealand Collection was started by the late lawyer, historian and member of Parliament Dr Robert McNab when he donated more than 4000 books and other publications from his personal library in 1913.
Also in Dunedin, the Reed Collection comprised more than 10,000 items, including those donated by Reed Publishing founder A. H. Reed in 1948.
A library spokeswoman said the bulk of special and rare books were donated, usually by relatives of a deceased collector.
"We get a steady trickle of people coming in with books they've found or which have been in the family for years.
"Ninety-nine percent of the time it's something we already have a copy of or an earlier edition of.
"It's fairly rare that we get something brought in that we haven't seen and want for our collections.
"Historically, the city has benefited from big bequests, but it just doesn't happen any more," she said.
