Social media has become a strategic driver of sponsorship effectiveness in major sporting events. At the 2024 Paris Olympics, digital platforms transformed how sponsorship relationships are formed, sustained, and activated for audience engagement. Yet, the mechanisms through which social media management influences sponsorship outcomes remain underexplored. This study examines the mediating role between core sponsorship antecedents – sport involvement, event attachment, brand familiarity, and sponsor-event congruence – and engagement outcomes. A quantitative survey of 7,412 Greek spectators was analyzed using structural equation modeling to test the proposed framework integrating sponsorship management and digital strategy. Results confirm that social media substantially amplifies the impact of sponsorship factors, fostering stronger sponsor–spectator connections and enhancing sponsorship returns. This is the first empirical model to link social media usage as a mediating variable between sponsorship antecedents and engagement outcomes in the context of mega-events, with a focus on the Paris 2024 Olympics. The research contributes to theory by positioning social media as a critical mediator in sponsorship strategy and offers actionable insights for managers seeking to optimize sponsorship effectiveness across diverse cultural and event contexts.