To test the effects of a cognitive-behavioral intervention for weight bias internalization (WBI; i.e., self-stigma) combined with behavioral weight loss (BWL). Adults with obesity and elevated WBI were randomly assigned to BWL alone or combined with the Weight Bias Internalization and Stigma Program (BWL + BIAS). Participants attended weekly group meetings for 12 weeks, followed by 2 biweekly and 2 monthly meetings (26 weeks total). Changes at Week 12 on the Weight Bias Internalization Scale (WBIS) and Weight Self-Stigma Questionnaire (WSSQ) were the principal outcomes, with changes at Week 26 assessed as secondary outcomes. Other outcomes included changes in mood, body image, eating behaviors, self-monitoring, and weight. Seventy-two participants were randomized (84.7% female, 66.7% Black, mean age = 47.1 ± 11.5 years) Linear mixed models showed no significant differences between the BWL + BIAS and BWL groups in WBIS changes at Week 12 (-1.3 ± 0.2 vs. -1.0 ± 0.2) or week 26 (-1.5 ± 0.2 vs. -1.3 ± 0.2). BWL + BIAS participants had greater reductions in WSSQ total scores at Week 12 (p = .03), with greater changes on the self-devaluation subscale at Weeks 12 and 26 (p ≤ .03). BWL + BIAS participants reported significantly greater benefits on measures of eating and self-monitoring. Percent weight loss at Week 26 did not differ significantly between groups (BWL + BIAS = -4.5 ± 1.0%, BWL = -5.9 ± 1.0%, p = .28). A psychological intervention for WBI produced short-term reductions in some aspects of weight self-stigma in persons with obesity. (PsycInfo Database Record (c) 2020 APA, all rights reserved).