Cyberbullying is attracting social, political, and academic interest as the use of electronic devices such as computers and mobile phones by young people has increased dramatically. However, little is known about the factors involved in their perpetration, particularly in the context of college students’ dating relationships. The aim of this study is to examine the involvement of college students in cyberbullying in the context of their dating relationships and to explore the impact of sexism on males’ cyberbullying of their girlfriends. Participants are 219 undergraduate students from a university in the south of Spain. Results showed that 48.4% of participants reported having bullied their partners during the last year via mobile phone and 37.5% via Internet. Males reported a greater extent of cyberbullying of their girlfriends through both means. Regression analyses indicated that males’ levels of hostile sexism are related to males’ cyberbullying of their girlfriends. These findings suggest a modernization in the forms of violence toward women among college students and also expand current literature by revealing the influence of participants’ hostile sexism on this type of cyber aggression against women in dating relationships.