Objective: Eating disorders (EDs) and depression are impacting youth at alarming rates, yet most adolescents do not access treatment. Single-session interventions (SSIs) can reach youth in need. This pilot examines the acceptability and short-term utility of an SSI designed to help adolescents adopt a body neutrality mindset. Method: Pre- to post-intervention data was collected, and within-group effect sizes and 95% confidence intervals were computed, to evaluate the immediate effects of the SSI on hopelessness, functionality appreciation, and body dissatisfaction. Patterns of use, demographics, program feedback, and responses from within the SSI were also collected. Results: The SSI and all questionnaires were completed by 75 adolescents (ages 13-17, 74.70% White/Caucasian, 48.00% woman/girl) who reported elevated body image and mood problems. Analyses detected significant pre-post improvements in hopelessness (dav = 0.60, 95% CI 0.35, 0.84; dz = 0.77, 95% CI 0.51, 1.02), functionality appreciation (dav = 0.72, 95% CI 0.46, 0.97; dz = 0.94, 95% CI 0.67, 1.21), and body dissatisfaction (dav = 0.61, 95% CI 0.36, 0.86; dz = 0.76, 95% CI 0.50, 1.02). The SSI was rated as highly acceptable, with a mean overall score of 4.34/5 (SD = 0.54). Qualitative feedback suggested adolescents' endorsement of body neutrality as a personally-relevant, helpful target for intervention. Discussion: This evaluation supports the acceptability and preliminary effectiveness of a body neutrality-focused SSI for adolescents with body image and mood concerns.