After the initial popularity of the comic strip British Lion Films announced a Modesty Blaise film to be written by Sidney Gilliat that was never made.

A film entitled Modesty Blaise, loosely based on the comic strip, was filmed in 1966 as a comedy thriller. It was directed by Joseph Losey and starred Monica Vitti as Modesty, Terence Stamp as Willie Garvin, and Dirk Bogarde as Gabriel. Peter O’Donnell wrote the first draft of the screenplay for the film, but the script was heavily revised by others before shooting began, and the finished film bore very little resemblance to O’Donnell’s vision in tone, theme, or characterisation. For example, a romance is established between Willie and Modesty, even though the comic strip firmly established only a platonic relationship between them. The film also incorporated several musical numbers. One sequence of the film establishes that the Modesty Blaise comic strip exists within the fictional universe of the film and is based upon the exploits of Vitti’s character, who is seen dressing up as the illustrated version of herself. The film was unsuccessful.

In 1982, a one-hour pilot was made for a proposed Modesty Blaise television series, starring Ann Turkel as Modesty Blaise and Lewis Van Bergen as Willie Garvin. The film aired on the ABC Network to positive reviews, but no series resulted. This was a slightly more serious version of the stories than the campy 1966 comedy version. In this pilot the setting is moved from London to Hollywood, and both Willie and Tarrant are portrayed as Americans; Modesty’s nationality is left unrevealed, however Turkel also plays her with an American accent.

In 2003, a direct-to-video film titled My Name Is Modesty was released under the „Quentin Tarantino Presents…“ banner. The film was directed by Scott Spiegel and starred English actress Alexandra Staden as Modesty Blaise (to date the only British actress to play the role on screen). Although promoted as the first of a series, no others were made. One immediately noticeable difference between the film and the source material is that it is a prequel to Modesty’s established backstory as a crime boss; as such, the character of Willie Garvin is omitted.

Quentin Tarantino has been interested in directing a Modesty Blaise film for many years, and at one point Neil Gaiman wrote a script treatment based upon O’Donnell’s novel, I, Lucifer. So far, nothing has come of these plans. Tarantino „sponsored“ the release of My Name Is Modesty by allowing it to be released under the label „Quentin Tarantino presents …“ In the Tarantino film Pulp Fiction, Vincent Vega is seen reading a copy of Modesty Blaise. Nicole Kidman has also gone on record as being interested in making a Modesty Blaise film, and Jennifer Lopez was reported to be pitching for the part in 2003.