Insecure and unresolved/disorganized attachment states of mind may impact affect regulation and interpersonal functioning that contribute to binge eating in women with binge‐eating disorder (BED). Group psychological treatment may facilitate changes from insecure to secure and from unresolved–disorganized to non‐unresolved/disorganized attachment states of mind. This study used attachment theory to understand better the psychopathology of BED and co‐morbid overweight status and to understand better the treatment response of patients with BED who receive group psychotherapy. Women with BED attended group psychodynamic interpersonal psychotherapy and completed the Adult Attachment Interview pretreatment and 6 months posttreatment. Matched samples of overweight women without BED and normal‐weight women without BED completed the Adult Attachment Interview at 1 time point. Women with BED had significantly higher rates of preoccupied and unresolved/disorganized attachment states of mind compared to normal‐weight women without BED and had similar rates of insecure and unresolved/disorganized attachment states of mind compared to overweight women without BED. Of the women with BED who had an insecure and/or unresolved/disorganized attachment states of mind at pretreatment, about 60% demonstrated clinically relevant changes to secure and to non‐unresolved/disorganized states of mind at 6 months post group psychodynamic interpersonal psychotherapy. Results indicated that some women with BED may benefit from interventions that help them regulate hyperactivated affect and create coherent narratives. Both women with BED and overweight women without BED may benefit from treatments that help them develop more adaptive affect regulation strategies related to unresolved/disorganized attachment states of mind. Key Practitioner Messages A preoccupied attachment state of mind may be an underlying and maintaining factor for women with binge‐eating disorder Time‐limited psychodynamic and interpersonal group psychotherapies, like Group Psychodynamic Interpersonal Psychotherapy, may help those with binge‐eating disorder to process and organize their attachment memories which may lead to improved affect regulation and interpersonal functioning Psychological theories and treatment for binge‐eating disorder and overweight may benefit from considering the current impact of insecure and unresolved/disorganized attachment states of mind