<p>Adolescents often witness harmful online behavior as bystanders, yet their responses vary. Guided by a values-as-motivation perspective, this study tested whether personal values relate to adolescents' anticipated emotional and behavioral responses to cyberbullying, and whether prior exposure to harmful online content moderates these associations. Israeli adolescents (<i>N</i> = 308; ages 13–18, 57% girls) completed the PVQ-25 questionnaire and responded to four cyberbullying hypothetical scenarios (including three real-life scenario screenshots). Self-transcendence values were associated with more supportive bystander behavior and emotions and with less indifference. Conservation values were linked to more supportive emotions and fewer indifferent and offensive emotions but were not reliably related to behavior. Power values showed the opposite pattern: less supportive behavior and higher offensive emotions, as well as greater indifference and amusement. Moderation analyses indicated that exposure to harmful content strengthened the association between prosocial values and supportive behavior; positive associations emerged at medium and high exposure levels. Findings suggest that adolescents’ values are linked to both what they feel and what they do as online bystanders, especially when prior exposure makes value-based responding more salient.</p>