Posttraumatic headache (PTH) is a common post-concussive symptom (PCS) after pediatric concussion (i.e., mild traumatic brain injury). However, whether other outcomes are associated with PTH after concussion remains uncertain. We examined PTH in association with other outcomes (other PCS, pain, cognitive functioning) up to 6 months postinjury in a cohort of children with concussion (n = 138) as compared to mild orthopedic injury (OI; n = 58). At 10 days postinjury, children with concussion were divided into 4 headache subgroups based on parent responses on a standardized headache questionnaire: (i) no PTH, or (ii) new, (iii) worse, or (iv) chronic PTH. Children with OI who reported PTH at 10 days postinjury (n = 15) were excluded from analyses. Cognitive and somatic PCS were measured with weekly parent proxy and child ratings on the Health and Behaviour Inventory. Pain severity was assessed using weekly child self-report on a 10-point numerical rating scale. Cognitive functioning was assessed at 10 days, 3 months, and 6 months postinjury using the Fluid Cognition composite from the National Institutes of Health Toolbox Cognition Battery. Performance validity was also assessed at each assessment. Results from mixed effects linear regression models showed that children with PTH after concussion, in most cases irrespective of subgroup, had higher PCS, higher pain, and lower cognitive functioning compared to children without PTH and those with OI. Differences in PCS and pain were significant for 4-8 weeks postinjury, with the new PTH group experiencing the most delayed recovery of PCS and the chronic PTH group showing the most persistently elevated pain. Children with OI reported higher pain than children without PTH. Results were generally similar when children who failed validity testing were omitted from analyses. The findings indicate that the presence of PTH after concussion is associated with significantly worse outcomes compared to concussion without PTH or OI, especially in the first 4-8 weeks postinjury. Interventions to reduce or ameliorate PTH may help to hasten recovery and improve outcomes in children with concussion.