The horror spoof - filled with foul language and crude sexual humour - overtook last week's big hitters The Perfect Storm and The Patriot with takings of $42.5m (£27.6m) in its first weekend.
This makes the film, directed by Keenen Ivory Wayans, the second biggest movie success of the year after Mission: Impossible 2, which opened with takings of $57.8m (£38m)
High seas disaster movie The Perfect Storm, starring George Clooney - last weekend's champion - slipped down to the number two slot in its second week of release with $27m ($17.8m).
It was followed by Mel Gibson's American War of Independence epic The Patriot with takings of $15.5m (£10m).
Overall it was a strong weekend for the US box office - which has been struggling this summer to pull in audiences.
According to the tracking firm Exhibitor Relations, takings for the top 12 films were up 9% to $136m (£89m) over last weekend and up 26% from a year ago.
Trend-setting
Similarly, this time last year saw another crude teen comedy American Pie open at number one with $18.7m (£12m).
Industry observers point to American Pie as an early example of a growing and popular trend in coarse humour coming out of Hollywood - of which Scary Movie is the latest incarnation.
The film, which stars Wayans' two younger brothers Shawn and Marlon, combines elements of the hit Scream and I Know What You Did Last Summer.
Unlike these two films, however, Scary Movie offers up ample helpings of gratuitous male nudity, raunchy dialogue and chronic drug use.
Paul Dergarabedian, president of Exhibitor Relations, said of the film's instant success:
"This obviously tapped into something that audiences were looking for. Scary Movie came into the market with everything going for it - a genre that teens love and a great market campaign."
Screen dreams
Despite its target teen audience, however, exit polls indicated that adults over 25 comprised 30% of the audience.
The core audience was aged 18-24, and men made up 55% of the total.
It's likely to continue having a good run this month as it won't face serious competition from other comedies until Eddie Murphy's Nutty Professor sequel opens in the US on 28 July.
The weekend's other big release was Disney's The Kid, starring Bruce Willis, which bagged itself a respectable third place with takings of $12.5m (£8m).
Willis plays a 40-year-old workaholic image consultant who magically encounters his chubby eight-year-old self and who ends up teaching him what is missing from his life.
A spokesman from the film's distributor Buena Vista said: "It's a fantasy everybody would like to have happen, that ability to do it again."
Meanwhile DreamWorks' claymation comedy Chicken Run, from Aardman Animations, slipped two places to number five in its third week with $9.5m (£6m).