Anarchist architecture, also known as anarchitecture, is a term used to describe architecture with anarchist intentions, or architecture by people who unconsciously follow anarchist principles such as decentralization and self-organization. According to anarchist theorists, anarchitecture should be done for the needs of individuals or small communities instead of power structures, such as capitalism or the state, like conventional architecture. Examples include housing projects and conceptual art by anarchist architects, self-built houses in informal settlements and squatted buildings modified by the inhabitants.

Anarchist architecture starts from the premise that architecture is a political act and its main concern should be to fulfill the needs of a person or a small community instead of a power structure. It criticizes capitalist architecture, which is "increasingly commodified, sterile and elitist - part of a global capitalist system where urban space is equated with profit for a tiny few".

It differs from communist theories of housing distribution by giving responsibility to the individual instead of the government and by applying solutions readily available in the present, instead of making longer-term plans. While marxist architecture tried to overcome the division between the bourgeoisie class and the proletariat, architecture academic P. G. Raman argues, for anarchists each stratum of society, because of its peculiar history, develops different traditions of cooperation.

The book Architecture and Anarchism, by Paul Dobraszczyk, catalogued 60 projects with "forms of design and building that embrace the core values of traditional anarchist political theory". Those values are, according to Dobraszczyk, autonomy, voluntary association, mutual aid and self-organisation through direct democracy. On his book Housing: An Anarchist Approach, Colin Ward also cites the importance of informal economy and Local Exchange Trading Systems for the anarchist architecture to work out.

Anarchist architecture is deeply tied with the DIY culture. The structures often borrow elements from avant-garde architecture and art.

While anarchist architecture can be performed with explicit anarchist intentions, it can also be carried out unconsciously, as a community will simply react to their living conditions without the knowledge of anarchist theory.

The Italian anarchist architect Giancarlo De Carlo was an important figure in the development of anarchist architecture. De Carlo, who opened his office in 1950, was active in the Italian anti-fascist resistance and in the post-war anarchist movement. He saw libertarian socialism as the underlying force of his design and considered non-hierarchical participation of inhabitants as an important factor in his architecture. During the design of a housing project in the early 1970s for workers at the steel factory in Terni, De Carlo insisted that the workers were involved during the design process during working time, and that management should not be allowed to attend.

De Carlo's participatory design was opposed to the modernist architecture of his time. He heavily criticized the functionalism of modernism, which he viewed as "too simple and unsophisticated compared with the complexity of reality". De Carlo viewed, according to architecture professor John McKean, that modernism "had succumbed to rigid bureaucratization and become formalist and prescriptive of aesthetic codes". He accused the architectural profession of surrendering to the interest of people without any principles: "The expert exploiter of building areas, the manipulator of building codes, the cultural legitimator for the sacking of the city organized by financiers, politicians and bureaucrats". He wrote in 1970 that "architecture is too important to leave to the architects" and saw participation as a process of transforming "architectural planning from the authoritarian act which it has been up to now, into a process".