It was discovered during a regular house valuation and was thought to have been purchased by the vendor's family in Italy between 1894 and 1916.
Celia Curnow, ceramics consultant to Lyon & Turnbull said: "I have waited 30 years to see a plate of this quality outside a museum. We had interest from around the world, with many collectors flying in to Edinburgh for the sale as well busy phone lines and internet bidding.
"This is a record price for a piece of ceramic to be sold in Scotland. The new owner wishes to remain anonymous."
The estimate was £100,000 for the sale on December 8.
The 16in (40cm) dish (that was broken in two) appears to be one of a small group of large 'istoriato' plates decorated by Xanto in 1537 with scenes inspired by the Persian history. The front is decorated with a scene from the Life of Cyrus and shows Cyrus persuading the people of Persepolis to rise up against their Median rulers.
The reverse of the plate is as revealing as the front as it is fully inscribed by the artist and carries labels inscribed by previous owners of the plate. The three line inscription in Xanto's hand can be translated as: Cyrus favoured sent from Persia / Takes his side against Astyages so he will show him / That that which heaven arranges comes together whatever it may be / Francesco Xanto from Rovigo.
In the 2007 exhibition held at London's Wallace Collection devoted to Xanto, curator John Mallett described Xanto as "pottery-painter, poet, man of the Italian Renaissance".
Although nothing at all is known of his origins, his education, or his early years, archival evidence records Xanto working in Urbino in 1530 - the date of his earliest signed piece, a plate commemorating the coming New Year.
Over the following five years he produced a large body of work; each piece was signed in various manners, sometimes dated, and marked as a product of Urbino.
Such consistency in signing his work was unusual at the time; there is some suggestion that the artist was blacklisted after the labour troubles of 1530, and that his choice to sign his works might be in some way related to these difficulties.