Social media and terrorist financing (SMTF) refers to how terror organisations (TO), sometimes called violent extremist organisations (VEOs), have exploited free social media platforms to raise money for terrorism/fighting/jihad, to recruit, train, equip, and transport fighters, to support extremist religious proto-states (e.g., Islamic State of Iraq and Syria [ISIS]), to market/brand an organisation including to disseminate its ideologies, and/or to amass wealth. This chapter considers the scope of SMTF and legal/policy responses to its ever-evolving practices, discusses how it is practised and by whom, and considers the challenges of fighting SMTF. SMTF is part of the larger concept of cyberterrorism where terrorists target computer systems maliciously and use digital technology to facilitate terror attacks, though some argue that these two actions are completely different phenomena. The chapter concludes by summarising the key points of the discussion, offering suggestions for future study of this phenomenon, and reflecting on the societal impacts of SMTF.