Adele's Someone Like You has become the first single to sell more than a million copies this decade, the Official Charts Company said.
It spent four weeks at number one in February before bouncing back to the top of the chart for another week in March.
The song caught the nation's attention after the singer songwriter's performance at the Brit Awards in February this year.
Since 2000, only 16 singles have reached the million sales mark. The last singles to hit that were Poker Face by Lady Gaga and I Gotta Feeling by the Black Eyed Peas, both released in 2009.
In contrast to Adele, six of the million-sellers achieved this feat on the back of reality television shows such as Pop Idol and X Factor.
Will Young's Anything Is Possible/Evergreen sold 1.8 million copies after he won Pop Idol in 2002, and tops the list of this century's biggest sellers.
Adele's latest album 21 has spent 16 weeks at the top of the Official Albums Chart.
It has so far sold 2.6 million copies. Her first album, 19, has also doubled its sales this year, with 800,000 copies.
Official Charts Company managing director Martin Talbot said: "With an almost certain Mercury Music Prize nomination and 21's first Christmas season to come, I suspect her record-breaking antics are not over yet."