There is a growing body of evidence to suggest that there has been a determined effort by Al Qaeda, and more recently Islamic State, to recruit petty and street criminals into their networks. Despite this, and increasing global concern, there exists very little scholarly literature exploring this phenomenon, particularly empirically grounded. This article directly addresses this gap in research, and is one of the, if not the, first to present an analysis underpinned by qualitative empirical interview data, collected from former extremists and active grassroots workers in the United Kingdom. The article determines that through religious and social justifications offered to reduce moral concerns, extremists encourage criminals to continue, intensify, and diversify their criminality, with intentions to fund violent extremist activity, or to create social unrest within society. Rather than attempting to change behavior, this is about reconstructing criminals’ motivations; a consideration that has wider implications for counterterrorism policy and operations.