It sold more than 702,000 copies, according to industry figures released on Wednesday.
The album, which features tracks from Jay-Z, Nas, Gang Starr and Macy Gray, beat new releases from Christina Aguilera and Nirvana to debut at number one.
It more than doubled the sales of Aguilera's Stripped, which sold 330,000 copies to put her at number two.
Behind Aguilera at number three was a greatest hits compilation from Seatle-based grunge band Nirvana, which sold approximately 234,000 copies.
Lagging well behind in the chart was Now or Never, the first solo album from Backstreet Boy Nick Carter, which sold just 68,000 copies in its first week.
White trash underclass
Eminem's chart success follows positive reviews for his debut movie, which premiered in Los Angeles on Wednesday.
The rapper arrived at the premiere sporting a pair of spectacles, a low-key woollen hat and casual T-shirt.
He joined a star-studded guest list that included Christina Aguilera, rap supremo Dr Dre, Pamela Anderson and Kid Rock.
Platinum-selling Eminem, recently reunited with his estranged wife Kim Mathers, debuts as an angry young white man named Jimmy 'Rabbit' Smith Jr.
His character is a talented product of the white-trash underclass of a bleak Detroit.
Loosely based on Eminem's real life story, 8 Mile focuses on a critical week in the life of Jimmy in which he raps his way to redemption, supported by a cast that includes Kim Basinger as his mother and Brittany Murphy as the love interest.
The hotly-tipped film is due for release in the UK on 13 January 2003.