This article asks: “How was the rhetoric of post or anti-fascism used to develop colonial projects in the inter and postwar period?” Through investigating the Du Bois archive, I answer this through producing a Du Boisian theory of colonial post-fascism. While many have written about the connections between European fascism and colonialism in theories of “colonial fascism,” a Du Boisian approach leads us to the concept of colonial post-fascism, demonstrating the array of colonial practices which were instigated in the name of world peace in the inter and postwar era. Colonial post-fascism is characterized by three processes that Du Bois wrote about. First, colonial post-fascism involves a bifurcation between colonial violence and peace, such that Western powers in the inter and postwar period could make commitments to world peace without interrogating the actions of their empires. Second, colonial post-fascism involves the process by which empires developed their imperial practices to rebuild from the effects of the war against fascism. Finally, colonial post-fascism involves the U.S. empire increasing its militarization, which developed in the fight against fascism, to secure colonial power under the rhetoric of maintaining world peace. This article makes several contributions. First, instead of highlighting the link between European fascism and colonialism, I demonstrate how colonialism shaped European post-fascism. Second, I contribute toward the project of undoing bifurcated histories of the West which elide discussions of colonial violence. Finally, I highlight how Du Bois’s involvement in the peace movement was not just activism, but also generative to social theory.