Objective Head injuries are a common presentation of children to Australian EDs. Healthcare documentation is an important tool for enhancing patient care. In our study, we aimed to assess the adequacy of paediatric head injury documentation in a mixed ED. Methods A retrospective analysis of presentations to a mixed ED between 2017 and 2018. Children aged <16 years old with a primary diagnosis of head injury were included. Documentation items based on local head injury guidelines were assessed in both medical and nursing documentation. We compared cases aged <1 and ≥1 year. Results There were 427 presentations that met the case definition. Medical documentation was present in 422 cases and nursing documentation in 310 cases. In combined medical and nursing documentation, items poorly documented include blood pressure (BP; 21.3%) and secondary survey (16.9%). In solely medical documentation, least commonly documented items are high‐risk bony injuries (22.5%), high‐risk soft tissue injuries (22.3%), seizure (22.0%) and non‐accidental injury (3.6%). Glasgow Coma Scale (GCS) was poorly documented in cases aged <1 year (10.9%, P < 0.001). Conclusions The largest gaps in the documentation of paediatric head injuries were BP and paediatric GCS in infants. Future audits and educational strategies should focus on targeting clinically relevant items that are predictive of serious outcomes.