Sexually transmitted infections (STIs) remain a major global health concern, contributing significantly to morbidity and facilitating the co-transmission of other pathogens. Recent outbreaks of Monkeypox virus (MPXV) have further underscored the urgent need for broad-spectrum antiviral agents effective against emerging and re-emerging sexually transmissible viruses. We report here the design and synthesis of a series of 3-cyanoquinoline-based Src inhibitors to evaluate their antimicrobial efficacy against sexually transmitted pathogens. Among them, compound 7d demonstrated potent inhibitory activity against MPXV, Herpes simplex virus types 1 and 2, Hepatitis C virus, Human immunodeficiency virus, and Chlamydia trachomatis at non-toxic concentrations. Owing to its broad-spectrum profile and favorable cytotoxicity profile, compound 7d represents a promising candidate for development as a topical microbicide for the prevention and treatment of STIs. Interestingly, the screening also identified compound 7g , which, despite lacking Src inhibitory activity, exhibited selective antiviral activity against members of the Poxviridae family, suggesting the involvement of alternative host-dependent mechanisms that can be further exploited. Both compounds were non-toxic in relevant epithelial and mucosal tissue models. Collectively, these findings highlight the therapeutic potential of 3-cyanoquinoline derivatives as scaffolds for the development of novel broad-spectrum microbicides targeting a range of sexually transmitted pathogens.