Techno-thrillers (or technothrillers) are a hybrid genre, drawing subject matter generally from science fiction, thrillers, spy, action, and war. They include a disproportionate amount (relative to other genres) of technical details on its subject matter (typically military technology); only science fiction tends towards a comparable level of supporting detail on the technical side. The inner workings of technology and the mechanics of various disciplines (espionage, martial arts, politics) are thoroughly explored, and the plot often turns on the particulars of that exploration.

Techno-thrillers tend to have a broad scope in the narrative, and can often be regarded as contemporary speculative fiction; world wars are a common topic. Techno-thrillers often overlap, as far as the genre goes, with near-future science fiction. To the extent that technology is now a dominant aspect of modern global culture, most modern thrillers are "techno-thrillers", and the genre is somewhat diffuse. The category of techno-thriller blurs smoothly into the category of hard science fiction; the defining characteristics of techno-thriller are an emphasis on real-world or plausible near-future technology. There is often a focus on military or military-political action. The techno-thriller genre also has substantial overlaps with the genres of conspiracy fiction and apocalyptic fiction.

Michael Crichton and Tom Clancy are considered to be the fathers of the "modern techno-thriller"; Crichton's book The Andromeda Strain and Clancy's book The Hunt for Red October set out the type example which defined the genre, although many authors had been writing similar material earlier. Nigel Balchin wrote earlier examples of similar stories during the 1940s. Other early examples of techno-thriller, written before the category had been well defined as a sub-genre, include Moonraker (1955) by Ian Fleming, Fail-Safe (1962) by Eugene Burdick and Harvey Wheeler, The Penetrators (1965) by Hank Searls (writing as Anthony Grey); Tree Frog by Martin Woodhouse (1966), North Cape (1969) by Joe Poyer, and Firefox by Craig Thomas (1977), later made into a movie, and Shuttle Down, by G. Harry Stine (writing as Lee Correy) (1981).