Although guidelines recommend extended surgical resection, radical resection and lymphadenectomy for patients with tumor stage (T)1b gallbladder cancer, these procedures are substantially underutilized. This population-based, retrospective cohort study aimed to evaluate treatment patterns and outcomes of 401 patients using the US Surveillance, Epidemiology, and End Results (SEER) database from 2004 to 2013. Results showed that median overall survival (OS) was 69 months for lymphadenectomy patients and 37 months for those without lymphadenectomy. Lymphadenectomy also tended to prolong cancer-specific survival (CSS), although the differences were not statistically significant. OS and CSS were similar for patients who received simple cholecystectomy and extended surgical resection. Cox proportional hazards regression models revealed survival advantages in patients with stage T1bN0 gallbladder cancer compared to those with stage T1bN1, and patients who received simple cholecystectomy plus lymphadenectomy compared to those who did not receive lymph node dissection. In further analyses, patients undergoing simple cholecystectomy who had five or more lymph nodes excised had better OS and CSS than those without lymph node dissection. In conclusion, survival advantages are shown for patients with T1b gallbladder cancer undergoing surgeries with lymphadenectomy. Future studies with longer follow-up and control of potential confounders are highly warranted.