This report examined baseline affective response to binge eating as a predictor of binge-eating disorder (BED) treatment outcome. Baseline affective response was defined as: (1) each individual's average net change (i.e., area under the curve [AUC]) of positive affect (PA) or negative affect (NA) before and after binge-eating episodes and (2) post-binge eating slope of PA or NA across seven-days of ecological momentary assessment (EMA). Adults with BED completed Integrative Cognitive-Affective Therapy (ICAT-BED) or cognitive behavioral therapy guided self-help (CBTgsh). Individuals with greater net increases in PA (AUC) following binge eating at baseline exhibited better treatment response in ICAT-BED at end-of-treatment and follow-up. NA affective response was only significant at end-of-treatment; individuals with less rapid post-binge improvements in NA (slope) did better in ICAT-BED, while individuals with lower net improvements in NA (AUC) did better in CBTgsh. Affective response to binge eating may be a marker of BED treatment response.