The Official Charts Company, which monitors sales in the United Kingdom, said Winehouse's release -- which included the single, "Rehab" and yielded the late performer five Grammy awards -- has sold 3.26 million copies, the BBC reported.
Those sales totals surpassed those of James Blunt's 2005 album, "Back to Bedlam."
"Back to Black" had dropped down the U.K. charts prior to Winehouse's death July 23. After she died, the album rocketed back up to number one, where it stayed for three weeks.
The third best-selling album in Britain so far this century is Dido's 2001 album "No Angel," which has sold more than 3.07 million, the BBC said.