ABSTRACT Drawing on the revised communication mediation model and the relative hostile media framework, this study examines the roles of political discussions in the relationship between social media news use and polarized partisan perceptions. Findings from a two-wave national survey conducted during the 2020 U.S. election cycle support our proposed model: political discussion and relative hostile media perception sequentially mediate the link between social media news use and affective polarization. Specifically, social media news consumption is associated with higher levels of both like-minded political discussion and cross-cutting political discussion. Like-minded discussion widens, while cross-cutting discussion narrows, the perceived hostility gap between counter-attitudinal and pro-attitudinal media outlets. Relative hostile media perception in turn predicts affective polarization among partisans. This study underscores the impacts of interpersonal discussion and media perception on democracy in the contemporary media and political landscape.