<p>Body image-related cyberbullying (BRC), which targets an individual’s body weight, shape, and size, poses a serious threat to adolescent mental health, particularly among females. Evidence suggests that adolescent females who act as cyberbystanders of BRC - those witnessing without being directly targeted - may experience heightened body dissatisfaction and maladaptive eating behaviours. However, the neurobiological mechanisms underlying BRC remain largely unexplored. This study developed a series of BRC scenarios to examine neural responses among adolescent female cyberbystanders to viewing BRC stimuli. A total of 24 scenarios (12 BRC, 12 neutral) were created to replicate social media posts. A sample of 413 females aged 14–19 rated the severity and realism of the BRC stimuli and completed measures of cyberbullying, body image, and eating disorder psychopathology. Results indicated a positive correlation between severity and realism ratings, with younger participants perceiving scenarios as more realistic. ARC-victimisation was associated with greater engagement in ARC-bullying behaviours and heightened body image disturbances. A final subset of six scenarios, reflecting varied severity, realism, and thematic content, was selected to form the Body Image-Related Cyberbullying Picture Series (BRC-PicS). This validated tool enables real-time investigation into BRC’s impact on adolescent female mental health, supporting future neurobiological research and informing interventions for body dissatisfaction and eating disorders among adolescent females.</p>