Background: Use of adjuvant chemotherapy (CTx) and chemoradiation therapy (cXRT) for the treatment of gallbladder cancer (GBC) remains varied. We sought to define the utilization and effect of adjuvant therapy for patients with GBC. Methods: Using a multi-institutional national database, 291 patients with GBC who underwent curative-intent resection between 2000 and 2015 were included. Patients with metastasis or an R2 margin were excluded. Results: Median patient age was 66.6 years. Most patients had a T2 (46.2 %) or T3 (38.6 %) lesion, and 37.8 % of patients had lymph node (LN) metastasis. A total of 186 (63.9 %) patients underwent surgery alone, 61 (21.0 %) received CTx, and 44 (15.1 %) patients received cXRT. On multivariable analysis, factors associated with worse overall survival (OS) included T3/T4 stage [hazard ratio (HR) 1.82], LN-metastasis (HR 1.84), lymphovascular invasion (HR 2.02), perineural invasion (HR 1.42), and R1 surgical margin status (HR 2.06); all P < 0.05). In contrast, receipt of CTx/cXRT was associated with improved OS (CTx, HR 0.38; cXRT, HR 0.26; P < 0.001) compared with surgery alone. Similar results were observed for disease-free survival (DFS) (CTx, HR 0.61; cXRT, HR 0.43; P < 0.05). Of note, only patients with high-risk features, such as AJCC T3/T4 stage (HR 0.41), LN metastasis (HR 0.45), and R1 disease (HR 0.21) (all P < 0.05) derived an OS benefit from CTx/cXRT. Conclusions: Adjuvant CTx/cXRT was utilized in 36 % of patients undergoing curative-intent resection for GBC. After adjusted analyses, CTx/cXRT were independently associated with improved long-term outcomes, but the benefit was isolated to only patients with high-risk characteristics.