Introduction Improvements in life expectancy imply that an increase of geriatric trauma patients occurs. These patients require special attention due to their multiple comorbidity issues. The aim of this study was to assess the impact of the implementation of geriatric comanagement (GC) on the allocation and clinical outcome of geriatric trauma patients. Methods This observational cohort study aims to compare the demographic development and the clinical outcome in geriatric trauma patients (aged 70 years and older) before and after implementation of a certified geriatric trauma center (GC). Geriatric trauma patients admitted between January 1, 2010 and December 31, 2010 were stratified to group pre-GC and admissions between January 1, 2018 and December 31, 2018 to Group post-GC. We excluded patients requiring end-of-life treatment and those who died within 24 h or due to severe traumatic brain injury. Outcome parameters included demographic changes, medical complexity (measured by American Society of Anaesthesiology Score (ASA) and Charlson Comorbidity Index (CCI)), in-hospital mortality and length of hospitalization. Results This study includes 626 patients in Group pre-GC (mean age 80.3 ± 6.7 years) and 841 patients in Group post-GC (mean age 81.1 ± 7.3 years). Group pre-GC included 244 (39.0%) males, group post-GC included 361 (42.9%) males. The mean CCI was 4.7 (± 1.8) points in pre-GC and 5.1 (± 2.0) points in post-GC (p <0.001). In Group pre-GC, 100 patients (16.0%) were stratified as ASA 1 compared with 47 patients (5.6%) in Group post-GC (p <0.001). Group pre-GC had significantly less patients stratified as ASA 3 or higher (n = 235, 37.5%) compared with Group post-GC (n = 389, 46.3%, p <0.001). Length of stay (LOS) decreased significantly from 10.4 (± 20.3) days in Group pre-GC to 7.9 (±22.9) days in Group post-GC (p = 0.011). The 30-day mortality rate was comparable amongst these groups (pre-GC 8.8% vs. post-GC 8.9%). Conclusion This study appears to support the implementation of a geriatric trauma center, as certain improvements in the patient care were found: Despite a higher CCI and a higher number of patients with higher ASA classifications, Hospital LOS, complication rates and mortality did were not increased after implementation of the CG. The increase in the case numbers supports the fact that a higher degree of specialization leads to a response by admitting physicians, as it exceeded the expectable trend of demographic ageing. We feel that a larger data base, hopefully in a multi center set up should be undertaken to verify these results.