The original drawings, showing bears, panthers, rhinos and other creatures, are roughly 32,000 years old.
President Francois Hollande toured the site on Friday - a copy of the closely-guarded Grotte Chauvet in the Ardeche region of southern France.
The original is closed to the public. The copy, at nearby Vallon-Pont d'Arc, is expected to attract many tourists.
The Chauvet drawings are believed to be the oldest cave art in the world. The limestone cave, with hundreds of vivid charcoal images, was discovered by potholers in 1994 and is now a Unesco World Heritage site.
The cave was closed off by a rock fall about 20,000 years ago, which meant the art was undisturbed by humans.
Unesco says the drawings are remarkable for the skilful use of shading, combinations of paint and engraving, anatomical precision and dynamism.
Specialists spent four years reproducing the cave with the help of hi-tech tools such as 3D imaging, AFP news agency reports. The painstaking project cost â‚¬55m (Â£40m; $58m).
The replica cave - the biggest in the world - will open to the public on 25 April.
France has inaugurated a giant replica cave containing reproductions of prehistoric drawings of animals.