This chapter traces the evolution of social movement theory to better understand how sport-based activism, particularly by racialized and marginalized groups, functions in the digital age. Moving from classical frameworks like resource mobilization theory and political process theory to the cultural turn of new social movement theory, it maps the shift from material demands to identity-based resistance and symbolic disruption. With particular attention to user-led digital activism, it explores how movements like Black Twitter and university athlete protests have fused online dissent with offline mobilization, challenging critiques of “slacktivism” and reframing digital platforms as legitimate spaces of activism. An interrogation on how media systems shape movement legitimacy, outcomes are measured beyond policy reform, and how sports remain a contested arena where both resistance and repression play out are investigated. The transformative potential of feminist-informed, decentralized, and media-savvy activism is examined offering a critical foundation for understanding how initiatives like Black Girl Hockey Club are reshaping the sport justice landscape through digital resistance and collective care.