More than 8,000 objects will be on display in the new area, 80% for the first time in generations.
The newly refurbished museum opens its doors on Friday.
The three-year programme has seen the original interior restored and storage areas turned into public space, making it one of the UK's largest museums.
It means the whole museum, situated in Chambers Street in the Old Town, will have 20,000 objects across 36 galleries.
Exhibits range from a life-sized skeleton cast of a Tyrannosaurus rex to specimens collected by Charles Darwin and 3,000-year-old mummies.
Sir Angus Grossart, chairman of the National Museums Scotland's board of trustees, said: "The reopening of the National Museum of Scotland, on time and within budget is a tremendous achievement as importantly it allows us to liberate the strengths of our great collections and mobilise their great potential for dynamic development.
"Our collections tell great stories about the world, how Scots saw that world, and the disproportionate impact they had upon it.
"The intellectual and collecting impact of the Scottish diaspora has been profound.
"It is an inspiring story which has captured the imagination of our many supporters who have helped us achieve our aspirations and to whom we are profoundly grateful."
Working with Scottish architect Gareth Hoskins and exhibition designer Ralph Appelbaum, National Museums Scotland has also restored Victorian architecture, created new galleries, a major gallery to host international exhibitions, a three-storey learning centre and a new street-level stone-vaulted entrance hall.
Glass elevators carry visitors from the entrance hall to the Grand Gallery, housing the UK's single largest museum installation, the Window on the World: a four-storey, 18-metre (59ft) high display of more than 800 objects.
Dr Gordon Rintoul, National Museums Scotland director, said: "This is a proud moment in the history of a great museum, the climax of a once-in-a-lifetime transformation through which we have rediscovered our exceptional collections, and breathed new life into a beautiful building.
"The result is a new National Museum of Scotland, a place where the cultures of Scotland and the world meet, and the arts and sciences connect."