Smith's In The Lonely Hour passed the 1 million landmark in the UK during the past 24 hours, making it only the second artist album to reach the landmark this side of the Atlantic.
The confirmation comes 24 hours after his album was confirmed a million-seller in the United States, by Nielsen Music.
Sam told OfficialCharts.com: "OFFICIALLY sold 1 MILLION copies of In The Lonely Hour! To say I am ecstatic is a huge understatement. Thank you so much to every single person who has purchased my album."
By Midnight last night, In The Lonely Hour had sold 1.007 million copies (based on Official Charts data), making it only the second artist album to achieve the feat in the UK this year, after Ed Sheeran's X hit the milestone at the end of November. In the US, Only Sam Smith, Taylor Swift and the Frozen soundtrack have passed the million-mark this year, according to Nielsen Music.
The success of Smith and Sheeran also makes 2014 the first year since 2011 when more than one album has passed 1 million sales in the UK ' in 2011, Adele's 21 and 19, Michael Buble's Christmas and Bruno Mars' Doo-Wops & Hooligans all passed 1 million sales.
In The Lonely Hour debuted Number 1 on the Official Albums Chart in May and June this year with impressive first-week sales of 102,000. It spent a second week at the top returning for a further fortnight 12 weeks later.
The record has also been a regular feature at the top end of the chart, having spent just one week outside the Top 5 since its release.
Sam's album has also spawned a string of successful singles, including Number 1s Money On My Mind and Stay With Me, as well as Top 10s I'm Not The Only One (Number 3) and Like I Can (9). To date, To date, tracks downloaded from his album total 2.48 million, have been streamed 87 million times and viewed on video streaming sites in the UK 48 million times