Background: Within the context of the widespread use of technologies by adolescents, the objectives of this study were to identify the perpetrators of intimate partner cyberstalking (IPCS) in adolescents; to analyze the relationship between IPCS and gender, age, sexting behaviors, pornography consumption, and ambivalent sexism; and to investigate the influence of the study variables as predictors of IPCS and determine their moderating role. Methods: Participants were 993 Spanish students of Secondary Education, 535 girls and 458 boys with mean age 15.75 (SD = 1.47). Of the total sample, 70.3% (n = 696) had or had had a partner. Results: Boys perform more sexting, consume more pornographic content, and have more hostile and benevolent sexist attitudes than girls. However, girls perpetrate more IPCS than boys. The results of the hierarchical multiple regression indicate that hostile sexism is a predictor of IPCS, as well as the combined effect of Gender × Pornography and Benevolent Sexism × Sexting. Conclusions: it is essential to implement sexual affective education programs in schools in which Information and Communication Technologies (ICT) are incorporated so that boys and girls can experience their relationships, both offline and online, in an egalitarian and violence-free way.