Background: Resected cholangiocarcinomas are rare and have high relapse rates. Adjuvant chemotherapy is the standard of care (BiLCAP Trial). Adjuvant radiation therapy benefit is not well defined. This study aims to evaluate survival outcomes of the effect of adjuvant chemoradiotherapy compared to chemotherapy in extrahepatic cholangiocarcinoma (EHC) using the National Cancer Database (NCDB). Methods: Patients with resected EHC between 2004 and 2013 were identified from the NCDB using ICD-O-3 histology and topography codes: 8140, 8160, 8161, 8162 and C24.0. Patients with neoadjuvant therapy were excluded from this analysis. Univariate and multivariable analyses were conducted, and Kaplan-Meier Curves were used to compare overall survival (OS) based on treatment received. Results: A total of 236 EHC patients were identified. Males comprised 60.6% and 88.1% were Caucasian. Median age was 64 (range, 31-84) years. The majority were distal (72.0%, N = 157) followed by perihilar (20.6%, N = 45), hilar (6.4%, N = 14) and cystic (0.9%, N = 2). Distribution across stages I-III was 28.8% (N = 68), 56.8% (N = 134), and 14.4% (N = 34), consecutively. Adjuvant chemotherapy was given in 37.7% (N = 89) and adjuvant chemoradiotherapy in 62.3% (N = 147). The median dose of radiation was 50.4 Gy. Adjuvant chemoradiotherapy was mostly given in regional node positive disease (p = 0.016) and negative surgical margin (p = 0.002) compared to regional node negative disease and positive surgical margin, respectively. The use of adjuvant chemoradiotherapy was associated with improved OS compared to chemotherapy alone in univariate (HR 0.64; 95% CI 0.44-0.93; p = 0.019) and multivariable analysis (HR 0.65; 95% CI 0.44-0.96; p = 0.030). Median survival and 1 year-OS for patients that received chemoradiotherapy was 33.8 months (95% CI 28, NA) and 87.7% (80.9%, 92.1%) compared to chemotherapy alone which was 23.8 months (95% CI 18.9, 35.4) and 75.5% (64.9%, 83.3%). Conclusions: Adjuvant chemoradiotherapy was associated with improved survival in patients with resected EHC compared to chemotherapy alone. This conclusion warrants further prospective studies to confirm these results.