Purpose: Current guidelines recommend chemotherapy (CT) with or without radiotherapy for unresected nonmetastatic gallbladder cancer (GC), with little consensus. However, several small-volume, single-institution studies have documented the efficacy of local therapy for this population. This is the largest study to date evaluating outcomes of chemoradiotherapy (CRT) versus CT alone in unresected nonmetastatic GC. Methods: The National Cancer Database was queried for primary GC cases (2004–2013) receiving CT alone or CRT. Patients receiving resection or lack of CT were excluded, as were those with metastatic disease or unknown M classification. Logistic regression analysis ascertained factors associated with CRT delivery. Kaplan-Meier analysis evaluated overall survival (OS) between both cohorts. Cox proportional hazards modeling determined variables associated with OS. Results: In total, 1,199 patients were analyzed (CRT: n=327, 27%; CT: n=872, 73%). Groups were evenly balanced, with no factor on multivariate logistic regression analysis statistically predicting for receipt of a particular paradigm. Median OS in the CRT and CT groups was 12.9 versus 7.8 months, respectively (P=.001). On multivariate analysis, OS was associated with age and years of treatment (P=.001 each). Notably, receipt of CRT independently predicted for improved OS (P=.001). Conclusions: CRT, compared with CT alone, was independently associated with improved survival in unresected nonmetastatic GC. Although causation is not implied, these results support the necessity for prospective CRT evaluation.