Traumatic brain injury (TBI) is a significant cause of disability, but little is known about sex and gender differences after TBI. We aimed to analyze the association between sex/gender, and the broad range of care pathways, treatment characteristics, and outcomes following mild and moderate/severe TBI. We performed mixed-effects regression analyses in the prospective multi-center Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study, stratified for injury severity and age, and adjusted for baseline characteristics. Outcomes were various care pathway and treatment variables, and 6-month measures of functional outcome, health-related quality of life (HRQoL), post-concussion symptoms (PCS), and mental health symptoms. The study included 2862 adults (36% women) with mild (mTBI; Glasgow Coma Scale [GCS] score 13-15), and 1333 adults (26% women) with moderate/severe TBI (GCS score 3-12). Women were less likely to be admitted to the intensive care unit (ICU; odds ratios [OR] 0.6, 95% confidence interval [CI]: 0.4-0.8) following mTBI. Following moderate/severe TBI, women had a shorter median hospital stay (OR 0.7, 95% CI: 0.5-1.0). Following mTBI, women had poorer outcomes; lower Glasgow Outcome Scale Extended (GOSE; OR 1.4, 95% CI: 1.2-1.6), lower generic and disease-specific HRQoL, and more severe PCS, depression, and anxiety. Among them, women under age 45 and above age 65 years showed worse 6-month outcomes compared with men of the same age. Following moderate/severe TBI, there was no difference in GOSE (OR 0.9, 95% CI: 0.7-1.2), but women reported more severe PCS (OR 1.7, 95% CI: 1.1-2.6). Men and women differ in care pathways and outcomes following TBI. Women generally report worse 6-month outcomes, but the size of differences depend on TBI severity and age. Future studies should examine factors that explain these differences.