The istoriato-style dish, which measures about 27cm (11in) in diameter, was expected to fetch between £80,000 and £120,000 during a live online sale by Lyon & Turnbull in Edinburgh.
Instead, the Italian work of art, which depicts the biblical story of Samson and Delilah, sold for an eye-watering £1,263,000 - a new world record, the auction house believes.
The rare dish is attributed to Nicola di Gabriele Sbraghe, who has been described as the "Raphael of maiolica painting".
It was made by him around 1520-1523 and was part of a sale of the contents of Lowood House, near Melrose in the Borders.
Ceramic specialists found the dish in a drawer when preparations were being made to auction off the 400-plus items in the collection.
Lyon & Turnbull managing director, Gavin Strang, who was on the rostrum when the dish sold, said: "As the auctioneer, it was a real joy to bring the hammer down at over £1 million on this incredibly rare dish - a new world record price I believe.
"The whole story of its discovery tucked away in a drawer, through the meticulous research carried out by our specialists, and then fierce international bidding on auction day has been exciting from beginning to end."
According to Mr Strang, it is "unprecedented" for maiolica - the type of pottery the dish is - from this period of Nicola's life to come on the market.