Current treatments for binge eating disorder (BED) and bulimia nervosa (BN) only show moderate efficacy, warranting the need for novel interventions. Impairments in food-related inhibitory control contribute to BED/BN and could be targeted by food-specific inhibitory control training (ICT). The aim of this study was to establish the feasibility and acceptability of augmenting treatment for individuals with BN/BED with an ICT app (FoodT), which targets motor inhibition to food stimuli using a go/no-go paradigm. Eighty patients with BED/BN receiving psychological and/or pharmacological treatment were randomly allocated to a treatment-as-usual group (TAU; n = 40) or TAU augmented with the 5-min FoodT app daily (n = 40) for 4 weeks. This mixed-methods study assessed feasibility outcomes, effect sizes of clinical change, and acceptability using self-report measures. Pre-registered cut-offs for recruitment, retention, and adherence were met, with 100% of the targeted sample size (n = 80) recruited within 12 months, 85% of participants retained at 4 weeks, and 80% of the FoodT + TAU group completing ≤8 sessions. The reduction in binge eating did not differ between groups. However, moderate reductions in secondary outcomes (eating disorder psychopathology: SES = -0.57, 95% CI [-1.12, -0.03]; valuation of high energy-dense foods: SES = -0.61, 95% CI [-0.87, -0.05]) were found in the FoodT group compared to TAU. Furthermore, small greater reductions in food addiction (SES = -0.46, 95% CI [-1.14, 0.22]) and lack of premeditation (SES = -0.42, 95% CI [-0.77, -0.07]) were found in the FoodT group when compared to TAU. The focus groups revealed acceptability of FoodT. Participants discussed personal barriers (e.g. distractions) and suggested changes to the app (e.g. adding a meditation exercise). Augmenting treatment for BED/BN with a food-specific ICT app is feasible, acceptable, and may reduce clinical symptomatology with high reach and wide dissemination.