A détournement (French: [detuʁnəmɑ̃]), meaning "rerouting, hijacking" in French, is a technique developed in the 1950s by the Letterist International, and later adapted by the Situationist International (SI), that was defined in the SI's inaugural 1958 journal as "[t]he integration of present or past artistic productions into a superior construction of a milieu. In this sense there can be no situationist painting or music, but only a situationist use of those means. In a more elementary sense, détournement within the old cultural spheres is a method of propaganda, a method which reveals the wearing out and loss of importance of those spheres."

The brand marketing specialist Douglas B. Holt defined it as "turning expressions of the capitalist system and its media culture against itself".

Détournement was prominently used to set up subversive political pranks, an influential tactic called situationist prank that was reprised by the punk movement in the late 1970s and inspired the culture jamming movement in the late 1980s.

Its opposite is recuperation, in which radical ideas or the social image of people who are viewed negatively are twisted, commodified, and absorbed in a more socially acceptable context.

In general it can be defined as a variation on previous work, in which the newly created work has a meaning that is antagonistic or antithetical to the original. The original media work that is détourned must be somewhat familiar to the target audience, so that it can appreciate the opposition of the new message. The artist or commentator making the variation can reuse only some of the characteristic elements of the originating work.

Détournement is similar to satirical parody, but employs more direct reuse or faithful mimicry of the original works rather than constructing a new work which merely alludes strongly to the original. It may be contrasted with recuperation, in which originally subversive works and ideas are themselves appropriated by mainstream media. Détournement, on the other hand, makes it possible for the images produced by the spectacle get altered and subverted so that rather than supporting the status quo, their meaning becomes changed in order to put across a more radical or oppositional message.

Guy Debord and Gil J. Wolman categorized détourned elements into two types: minor détournements and deceptive détournements. Minor détournements are détournements of elements that in themselves are of no real importance such as a snapshot, a press clipping, an everyday object which draw all their meaning from being placed in a new context. Deceptive détournements are when already significant elements such as a major political or philosophical text, great artwork or work of literature take on new meanings or scope by being placed in a new context. For Debord, a détournement is a way to expose explicitly the inner workings of the objective reality of the Spectacle, thus creating a window for criticism.

In the United States, Frank Discussion is widely known for his use of détournement in his works dating from the late 1970s through the present, particularly with the Feederz. The use of détournement by Barbara Kruger familiarised many with the technique, and it was extensively and effectively used as part of the early HIV/AIDS activism of the late 1980s and early 1990s. Examples of contemporary detournement include Adbusters' "subvertisements" and other instances of culture jamming, as well as poems composed collaboratively by Marlene Mountain, Paul Conneally, and others, in which quotations from such famous sources as the Ten Commandments and quotations by United States President George W. Bush are combined with haiku-like phrases to produce a larger work intended to subvert the original source. The comic artist Brad Neely's reinterpretation of Harry Potter, Wizard People, took Warner Bros.' first Harry Potter film, The Sorcerer's Stone, and substituted the original soundtrack with a narration that casts the hero as a Nietzschean superman.