Neo-Marxism is a loose term for various twentieth-century approaches that amend or extend Marxism and Marxist theory, usually by incorporating elements from other intellectual traditions, such as: critical theory, psychoanalysis or Existentialism (in the case of Sartre).

Erik Olin Wright's theory of contradictory class locations, which incorporates Weberian sociology, critical criminology, and anarchism, is an example of the syncretism in neo-Marxist theory. As with many uses of the prefix neo-, many theorists and groups designated as neo-Marxist have attempted to supplement the perceived deficiencies of orthodox Marxism or dialectical materialism. Many prominent neo-Marxists, such as Herbert Marcuse and other members of the Frankfurt School, were sociologists and psychologists.

Neo-Marxism comes under the broader framework of the New Left. In a sociological sense, neo-Marxism adds Max Weber's broader understanding of social inequality, such as status and power, to Marxist philosophy. Strains of neo-Marxism include: critical theory, analytical Marxism and French structural Marxism.

The concept arose as a way to explain questions which were not explained in Karl Marx's works. There are many different "branches" of Neo-Marxism often not in agreement with each other and their theories.