Family accommodation (FA) involves the actions taken by family members, particularly parents, to accommodate a child´s obsessive–compulsive disorder (OCD) symptoms, reducing distress or impairment. This behavior may maintain compulsive and avoidant behavior, preventing corrective learning or habituation. This study aims to investigate the prevalence and factors influencing FA in a large Scandinavian sample of children with OCD. We assessed 238 children using standardized diagnostic interviews, OCD symptom severity assessments and questionnaires evaluating functional impairment and internalizing and externalizing symptoms. FA was measured using the Family Accommodation Scale, a 12-item clinician-rated interview. Our results confirmed a high frequency of accommodation, with approximately 70% of primary caregivers reporting some accommodation daily and 98% at least once per week. FA was associated with increased OCD symptom severity, contamination/cleaning symptoms, internalizing and externalizing behavior, and functional impairment. Linear regression analysis showed that high levels of FA are specifically associated with lower age, higher OCD symptom severity, parent-reported impairment, internalizing, and externalizing symptoms. A path analysis revealed that FA partially mediated the relationship between OCD severity, externalizing symptoms, and child’s age, highlighting the role of FA in the progression of OCD and related symptoms. The findings emphasize the importance of evaluating FA before initiating treatment and specifically addressing it during the therapeutic process.