It shows a side profile of the 88-year-old monarch wearing a crown and drop earrings.
It is only the fifth definitive coin portrait to have been created during her 63-year reign.
Coins featuring the new image will go into production from Monday but will only appear in circulation later this year.
The portrait was designed by engraver Jody Clark, whose design was selected in a competition organised by the Royal Mint Advisory Committee, a consultative panel to HM Treasury.
Mr Clark, 34, said: "I hope that I've done Her Majesty justice and captured her as I intended, in a fitting representation.
"The news that my design had been chosen was quite overwhelming, and I still can't quite believe that my royal portrait will be featured on millions of coins."
Adam Lawrence, chief executive of the Royal Mint, said the change of royal portrait made 2015 a "vintage year" for UK coins.
He added: "Capturing a portrait on the surface of a coin demands the utmost skill, and is one of the most challenging disciplines of the coin designer's art."
The winning art work was recommended to the Chancellor, and then the Queen, for final approval.
The Royal Mint has unveiled a new coinage portrait of the Queen.