Autonomism or autonomismo, also known as autonomist Marxism or autonomous Marxism, is an anti-capitalist social movement and Marxist-based theoretical current that first emerged in Italy in the 1960s from workerism (operaismo). Later, post-Marxist and anarchist tendencies became significant, after influence from the Situationists, the failure of Italian far-left movements in the 1970s, and the emergence of a number of important theorists including Antonio Negri, who had contributed to the 1969 founding of Potere Operaio, as well as Mario Tronti, Paolo Virno, and Franco Berardi.

George Katsiaficas summarizes the forms of autonomous movements by saying that "[i]n contrast to the centralized decisions and hierarchical authority structures of modern institutions, autonomous social movements involve people directly in decisions affecting their everyday lives, seeking to expand democracy and help individuals break free of political structures and behavior patterns imposed from the outside." This has involved a call for the independence of social movements from political parties, in an anti-authoritarian revolutionary perspective that seeks to create a practical political alternative to authoritarian socialism, state socialism, and contemporary representative democracy.

Autonomism influenced the German Autonomen and remains influential in Italy, France, and to a lesser extent the English-speaking countries. In the 21st century, those who describe themselves as autonomists now vary from Marxists to anarchists.

Early theorists, like Mario Tronti, Antonio Negri, Sergio Bologna, and Paolo Virno, developed notions of "immaterial" and "social labour" that extended the Marxist concept of labour to all society. They suggested that modern society's wealth was produced by unaccountable collective work, and that only a little of this was redistributed to the workers in the form of wages. Other Italian autonomists—particularly Marxist feminists, such as Mariarosa Dalla Costa and Silvia Federici—emphasised the importance of feminism and the value of unpaid female labour to capitalist society. Michael Ryan, a scholar of the movement, writes:

Autonomy, as a movement and as a theory, opposes the notion that capitalism is an irrational system which can be made rational through planning. Instead, it assumes the workers' viewpoint, privileging their activity as the lever of revolutionary passage as that which alone can construct a communist society. Economics is seen as being entirely political; economic relations are direct political relations of force between class subjects. And it is in the economic category of the social worker, not in an alienated political form like the party, that the initiative for political change resides.

In Empire, Negri and Michael Hardt argue that network power constructs are the most effective methods of organization against the neoliberal regime of capital accumulation and predict a massive shift in the dynamics of capital into a 21st century empire.

In West Germany, Autonome was used during the late 1970s to depict the most radical part of the political left.

Within the context of the movement of 1977, riots took place in Bologna on 11 March 1977 following the killing of student Francesco Lorusso by police. Beginning in 1979, the state effectively prosecuted the autonomist movement, accusing it of protecting the Red Brigades, which had kidnapped and assassinated Aldo Moro. 12,000 far-left activists were detained; 600 fled the country, including 300 to France and 200 to South America.