Purpose: The aim of this study was to determine whether the outcomes of patients with hemodynamically unstable pelvic bone fractures changed after the introduction of a protocol including extraperitoneal pelvic packing (EPP) and the establishment of a trauma center. Methods: We analyzed data of adult patients (≥ 18 years old) with hemodynamically unstable pelvic bone fractures who visited a single trauma center from February 2009 to October 2016. In July 2014, a new protocol for pelvic fractures was implemented, and a trauma center was established. Therefore, patient outcomes were compared by period (period I: pre-protocol vs. period II: post-protocol). Results: Seventy-nine patients with hemodynamically unstable pelvic bone fractures were recruited. The time to angiographic embolization after arrival at the emergency room decreased significantly in period II when compared to period I (182.9 vs. 268.9 min, respectively, p < 0.001). The time required to intervention, including EPP, also decreased, from 268.9 ± 132.4 min in period I to 141.9 ± 79.9 min in period II (p < 0.001). The overall mortality rate decreased from 47.2% in period I to 23.3% in period II (p = 0.033), and mortality related to hemorrhagic shock in particular, was significantly lowered, from 27.8% in period I to 4.7% in period II (p = 0.009). Conclusions: The establishment of a trauma center and the implementation of a new protocol that included EPP were effective in the treatment of patients with hemodynamically unstable pelvic fractures.