The digit will be part of a landmark exhibition marking the 400th anniversary of his first observations of the skies.
The finger – the middle digit from Galileo's right hand – is mounted on a marble base and encased in a crystal jar.
It will be among 250 objects which will go on display in Florence as part of an exhibition entitled Galileo: Images of the Universe from Antiquity to the Telescope, which opens next month in Florence.
The finger was removed when the astronomer's body when it was exhumed from his unconsecrated grave and transferred to a mausoleum in a Florentine church in 1737. It is usually on display at Florence's Museum of the History of Science.
Last month British and Italian scientists unveiled plans to exhume Galileo's body to determine whether a degenerative eye condition affected his observation of the planets in later life.
Researchers believe that Galileo could have been even more accurate in his work had he not been suffering from a genetic disease which eventually left him blind.
They are seeking permission from the Catholic Church to exhume the body.
Galileo, who lived from 1564 to 1642, was condemned by the Church for teaching that the Earth revolves around the Sun and in 1633 was tried and convicted of heresy by the Inquisition.
He spent the last nine years of his life under house arrest.
But the Church's position on Galileo has recently softened.