Background This is the final report evaluating the long-term outcomes of a single-arm phase II clinical trial that demonstrated the short-term efficacy of laparoscopic gastrectomy (LG) for highly advanced gastric cancer (AGC) KUGC04. Patients and Methods Seventy-three patients with histologically confirmed gastric adenocarcinoma and diagnosed with clinical stage II or higher, who potentially underwent curative resection between August 2009 and November 2014, were prospectively enrolled. Long-term outcomes with 5-year progression-free survival (PFS) and 5-year overall survival (OS) were evaluated according to clinical or pathological stages. Recurrence and progression patterns were also investigated. These outcomes were compared with those of previous reports to assess the applicability of LG for highly advanced gastric cancer (HAGC). Results The median observation period of all surviving patients was 75.1 months. The 5-year PFS and 5-year OS of all patients was 47.4% and 54.4%, respectively. Clinical stage-specific 5-year PFS and 5-year OS was 75.0, 69.1, 53.9, 39.4, 40.0 and 9.1, and 75.0, 68.8, 61.5, 45.0, 60.0 and 27.3, respectively, in stages IIA, IIB, IIIA, IIIB, IIIC, and IV, respectively. Pathological stage-specific 5-year PFS and 5-year OS, including ypStage with preoperative chemotherapy, was 100, 80.0, 100, 62.5, 80.0, 51.3, 16.7, 22.2 and 12.5, and 100, 80.0, 100, 75.0, 80.0, 64.2, 25.0, 33.3 and 12.5, respectively, in stage X (no residual tumor with preoperative chemotherapy), IA, IB, IIA, IIB, IIIA, IIIB, IIIC, and IV, respectively. Recurrence or progression was observed in 30 patients (41.1%). Conclusion LG for HAGC performed by experienced surgeons is safe and oncologically acceptable.