Uncertainties remain about the most effective treatment for uterine carcinosarcoma (UCS), a rare but aggressive uterine cancer, due to the limited scope for randomized trials. This study investigates whether nodal excision or adjuvant therapies after hysterectomy offer a survival benefit, using multi-institutional clinical registry data from South Australia. Data for all consecutive cases of UCS from 1980 to 2019 were extracted from the Clinical Cancer Registry. Clinical and treatment-related factors associated with disease-specific mortality (DSM) and all-cause mortality (ACM) were determined using multivariable Cox proportional hazards regression, with subgroup analyses by stage. Median follow-up for the 140 eligible cases was 21 months. 94% underwent hysterectomy, and 72% had an additional pelvic lymph node dissection (PLND). Furthermore, 16% received adjuvant chemotherapy; 11% adjuvant radiotherapy and 16% multimodal chemoradiotherapy, with an increase in the latter two modalities over time. DSM was reduced among those who underwent PLND (HR: 0.41; 95%CI: 0.23-0.74), adjuvant chemotherapy (HR: 0.39; 95%CI: 0.18-0.84) or multimodality treatment (HR: 0.11; 95%CI: 0.06-0.30) compared with hysterectomy alone for the whole cohort and for late stage disease (FIGO III/IV) but not for earlier stage disease, except for reduced DSM with multimodal therapy. Findings were similar for ACM. Our findings indicate better survival among those who received PLND, chemotherapy and multimodal adjuvant therapy, with the latter applying to early and late stage disease. However, cautious interpretation is warranted, due to potential "indication bias" and limited power. Further research into effective treatment modalities, ideally using prospective study designs, is needed.