(1) Background: Biliary tract cancers (BTCs) are a heterogeneous group of neoplasms with dismal prognosis and the role of adjuvant chemoradiotherapy in high-risk resected patients is unclear. (2) Methods: We retrospectively analyzed the outcomes of BTC patients who received curative intent surgery with microscopically positive resection margins (R1) and adjuvant chemoradioradiotherapy (CCRT) or chemotherapy (CHT) from January 2001 to December 201. (3) Results: Out of 65 patients who underwent R1 resection, 26 received adjuvant CHT and 39 adjuvant CCRT. The median recurrence-free survival (RFS) in the CHT and CHRT groups was 13.2 and 26.8 months, respectively (p = 0.41). Median overall survival (OS) was higher in the CHRT group (41.9 months) as compared to the CHT group (32.2 months), but the difference was not statistically significant (HR 0.88; p = 0.7). A promising trend in favor of CHRT was observed in N0 patients. Finally, no statistically significant differences were observed between patients undergoing adjuvant CHRT after R1 resection and patients treated with chemotherapy alone after R0 surgery. (4) Conclusions: Our study did not show a significant survival benefit with adjuvant CHRT over CHT alone in BTC patients with positive resection margins, while a promising trend was observed.