Purpose Child maltreatment is known to be associated with risk of later offending and victimisation in adolescence and adulthood, but only a few studies have examined justice system contact in childhood and none have focused on police contact. This study investigated the time to first contact with police in childhood (aged 13 years and younger) among children with prior child protection services contact.

Methods Using administrative data for 91,631 children from the New South Wales Child Development Study, Cox proportional hazards regression analyses were used to investigate the time to first contact with the police (for any reason, and specifically as a ‘person of interest’, ‘victim’ or ‘witness’) associated with prior child protection contact, during the observation period from birth to age 13 years. Multivariate models controlled for sex, Aboriginal and/or Torres Strait Islander background, and socioeconomic disadvantage. Subgroup analyses were also conducted for boys and girls separately.

Results Among the 14,323 children with any police contact by age 13 years, around half (52.3 %) had prior contact with the child protection system. Higher rates of police contact for any reason (HR = 4.45 [95 % CI = 4.08–4.86]), and as a person of interest (HR = 9.57 [95 % CI = 6.85–13.38]), victim (HR = 4.49 [95 % CI = 4.18–5.05]), or witness (HR = 9.56 [95 % CI = 7.19–12.69]) were associated with child protection services contact. Effect sizes were similar for boys and girls.

Conclusions Early interventions that specifically aim to prevent early contact with the justice system among vulnerable children and their families involved with child protection services are required.