Wearable fitness trackers are an increasingly popular tool for measuring physical activity (PA) due their accuracy and momentary data collection abilities. Despite the benefits of using wearable fitness trackers, there is limited research in the eating disorder (ED) field using wearable fitness trackers to measure PA in the context of EDs. Wearable fitness trackers are often underused in ED research because there is limited knowledge about whether wearable fitness trackers negatively or positively impact PA engagement and ED symptoms in individuals with EDs. The current study aimed to assess the perceived impact wearable fitness trackers have on PA engagement and ED symptoms over a 12-week CBT treatment for 30 individuals with binge eating and restrictive eating that presented to treatment engaging or not engaging in maladaptive exercise. Participants in the maladaptive exercise group (n = 17) and non-maladaptive exercise group (n = 13) wore a fitness tracker for 12 weeks and completed questionnaires assessing participants' perceptions of the fitness trackers' influence on ED symptoms and PA engagement throughout treatment. Results demonstrated a small percentage of individuals perceived the fitness tracker influenced ED behaviors or PA engagement, and there were mixed results on whether participants positively or negatively perceived the fitness tracker influenced them to engage in ED behaviors or PA engagement. Although preliminary, these results demonstrate the need to continue using objective measurements of PA via wearable fitness trackers to further our understanding of the positive and negative effects of fitness trackers on clinical ED samples.Level of Evidence: Level 1, randomized controlled trial.