The present cross-sectional study examined the chain mediating roles of spousal support and dyadic adjustment in the relationship between social media addiction and sexual functioning among 211 married women of reproductive age in Qazvin, Iran. Grounded in the Interpersonal Process Model of Intimacy, the study posited that excessive social media use displaces face-to-face interactions, thereby eroding emotional support and relational harmony, which are critical for sexual well-being. Participants completed validated measures assessing social media addiction, spousal support, dyadic adjustment, and sexual functioning through an online survey. Results showed that dyadic adjustment was positively associated with sexual functioning, while social media addiction negatively impacted sexual functioning through sequential reductions in spousal support and dyadic adjustment. More specifically, higher levels of social media addiction correlated with lower levels of spousal support, which in turn predicted poorer dyadic adjustment and subsequently diminished sexual functioning. The findings highlight the importance of dyadic adjustment as a mediator and underscore how spousal support buffers the detrimental effects of social media addiction on marital sexual health. These results suggest that interventions targeting couples' communication and support systems may mitigate the negative consequences of excessive social media use on intimate relationships.