Researchers have become increasingly interested in the saturation of popular Western culture by female hypersexualization. We provide data showing that men have more sexually aggressive intentions toward women who self‐sexualize, and that self‐sexualized women are vulnerable to sexual aggression if two qualifying conditions are met. Specifically, if perceivers view self‐sexualized women as sexually open and lacking agency (i.e., the ability to influence one's environment), they harbor more sexually aggressive intentions and view women as easier to sexually victimize. In Experiment 1, male participants viewed a photograph of a woman whose self‐sexualization was manipulated through revealing versus non‐revealing clothing. In subsequent experiments, men and women (Experiment 2) and men only (Experiment 3) viewed a photograph of a woman dressed in non‐revealing clothing but depicted as open or closed to sexual activity. Participants rated their perceptions of the woman's agency, then judged how vulnerable she was to sexual aggression (Experiments 1 and 2) or completed a sexually aggressive intentions measure (Experiment 3). Results indicated that both men and women perceived self‐sexualized women as more vulnerable to sexual aggression because they assumed those women were highly sexually open and lacked agency. Perceptions of low agency also mediated the relationship between women's perceived sexual openness and men's intentions to sexually aggress. These effects persisted even when we described the self‐sexualized woman as possessing highly agentic personality traits and controlled for individual differences related to sexual offending. The current work suggests that perceived agency and sexual openness may inform perpetrator decision‐making and that cultural hypersexualization may facilitate sexual aggression. Aggr. Behav. 42:483–497, 2016. © 2016 Wiley Periodicals, Inc.