Art intervention is an interaction with a previously existing artwork, audience, venue/space or situation. It is in the category of conceptual art and is commonly a form of performance art. It is associated with Letterist International, Situationist International, Viennese Actionists, the Dada movement and Neo-Dadaists. More latterly, intervention art has delivered Guerrilla art, street art plus the Stuckists have made extensive use of it to affect perceptions of artworks they oppose and as a protest against existing interventions.

Intervention can also refer to art and actions which enter a situation outside the art world in an attempt to change the existing conditions there. For example, intervention art may attempt to change economic or political situations, or may attempt to make people aware of a condition that they previously had no knowledge of. Since these goals mean that intervention art necessarily addresses and engages with the public, some artists call their work "public interventions".

Although intervention by its nature carries an implication of subversion, it is now accepted as a legitimate form of art and is often executed with the endorsement of those in positions of authority over the artwork, audience, or venue/space to be intervened in. However, unendorsed (i.e. illicit) interventions are common and lead to debate as to the distinction between art and vandalism. By definition it is a challenge, or at the very least a comment, related to the earlier work or the theme of that work, or to the expectations of a particular audience, and more likely to fulfil that function to its full potential when it is unilateral, although in these instances, it is almost certain that it will be viewed by authorities as unwelcome, if not vandalism, and not art.

Intervention art exists where an individual or group has strong enough beliefs to take perceived ethical action around social issues from materialism to war. Its origins within the history of art are evidenced by such work as Leonardo Da Vinci's "A cloudburst of material possessions" which depicts the artist taking a stand against the materialist status quo. Goya's Black etchings 1812–15 depict almost documentary evidence of actual war depravities. Both examples display the art of conscience.

These examples were made by artists who relied for their livelihoods on ruling class patronage so both were only posthumously made public.

Intervention art also contests the boundaries between the art world and the real world. Such interaction surfaced when artists started using found objects which they incorporated into painting. This began with Cubism around 1912 and the use of collage such as Kurt Schwitters' Merz.

For the remainder of the 20th century and into the early 21st century Intervention artists gravitated away from the market driven art back into the real world; "artists must be activists"... framing elephants in rooms."

There are many art interventions which are carried out in contexts where relevant invitation and approval has been given.