The movie, starring Brad Pitt, Christoph Waltz and Diane Kruger, pulls in £3.5 million on its opening weekend to knock last week's chart leader The Time Traveller's Wife into second place.
CG-animated comedy G-Force holds its place at number three, Ashley Tisdale's Aliens In The Attic falls two places to number four and the latest Harry Potter slips a place to five.
Wayans brothers spoof Dance Flick is the only other new release to make the chart at number six.
The UK box office top ten in full:
1. (-) Inglourious Basterds - £3,596,415
2. (1) The Time Traveller's Wife - £915,751
3. (3) G-Force - £654,909
4. (2) Aliens In The Attic - £642,522
5. (4) Harry Potter and the Half-Blood Prince - £598,335
6. (-) Dance Flick - £462,825
7. (5) GI Joe: The Rise Of Cobra - £455,536
8. (6) The Ugly Truth - £451,023
9. (8) Ice Age 3: Dawn Of The Dinosaurs - £336,300
10. (9) The Proposal - £270,691