Cognitive weaknesses have been implicated as a vulnerability factor in the development and maintenance of eating disorders. Despite this, cognitive styles are not routinely assessed in adult outpatient eating disorder programs and little is known about how they may impact patients' functional outcomes, psychological symptoms, or treatment engagement. The aim of this study was to evaluate thinking styles (i.e., cognitive rigidity and attention to detail) among adults attending specialized outpatient treatment for an eating disorder and assess whether such styles were associated with participants' satisfaction with life, psychological symptoms, and engagement in the outpatient group therapy program. Demographic and physical health information was collected from 95 adults who were eligible for an outpatient program. Participants completed the Detail and Flexibility Questionnaire, Satisfaction with Life Scale, Beck Depression Inventory second edition, and Beck Anxiety Inventory. Elevated scores for cognitive rigidity and attention to detail were transdiagnostic rather than specific to eating disorder diagnoses. Cognitive rigidity and attention to detail were associated with lower satisfaction with life, and increased anxiety and depression. Cognitive styles of cognitive rigidity and attention to detail were not associated with engagement in treatment or treatment completion. Cognitive patterns may be important for clinicians to evaluate as part of routine outpatient care given that they occur transdiagnostically and are linked with psychological symptoms and functional outcomes for adults struggling with an eating disorder.