Prior to the release of the film, O’Donnell novelised his version of the screenplay as a novel titled Modesty Blaise. This book was a critical and sales success, resulting in O’Donnell alternating between writing novels and writing the comic strip for the next 30 years. O’Donnell’s version of the screenplay was also used as the basis for a late-1990s Modesty Blaise graphic novel published by DC Comics.
According to Fox records, the film needed to earn $5,800,000 in rentals to break even and made $4,825,000, meaning it lost money.
Modesty Blaise was a moderate success at the time of its original release, Bosley Crowther, writing in The New York Times, characterised the film as „a weird film, all right. Maybe, if the whole thing were on a par with some of its flashier and wittier moments, or were up to its pictorial design, which is dazzling, it might be applauded as a first-rate satiric job.“ According to Crowther: „The scenery, a few pop-art settings and a gay, nonchalant musical score are indeed, about the only consistently amusing things about this whacky color film.“
Two more serious attempts at adapting the comic strip for the screen occurred in 1982 with a Modesty Blaise starring Ann Turkel as Blaise, and again in 2003 with My Name Is Modesty, a prequel starring Alexandra Staden in the title role and omitting the Willie Garvin character entirely.