The 3000-year-old artifact will be auctioned on July 4, as part of Christie's Exceptional Sale.
This brown quartzite head was part of a statue of the God Amen, which was the most important deity of ancient Egypt.
It bears the facial features of the Pharaoh Tutankhamen, easily recognizable with its full mouth with a slightly drooping lower lip and almond-shaped eyes.
Similar representations of the God Amen, also with facial features of the young pharaoh, were carved for the temple of Karnak in Upper Egypt, as part of the royal restoration program.
It is the first time that the sculpture, estimated to fetch £4 million (around $5.1 million), will appear on the open market since 1985.
It is being auctioned from the Resandro Collection, one of the world's most renowned private collections of Egyptian art -- part of which was sold for over £3 million (around $3.8 million) in 2016.
The high estimate on the head demonstrates an ever-growing global demand for statues of Tutankhamen, most of which are housed in international museums.
Although he ruled for less than ten years, Tutankhamen remains the most famous Egyptian Pharaoh in history.
His place in the cultural consciousness was secured by the discovery of his still-intact tomb in 1922 by archeologists Howard Carter and Lord Carnarvon.
The head of Tutankhamen as the God Amen will be auctioned on July 4 in Christie's headquarters in London. Additional information can be found at https://www.christies.com/