Patients with advanced melanoma resistant to immune checkpoint or BRAF/MEK inhibitors have treatment options with relatively low efficacy. Lifileucel, a one-time autologous tumor-infiltrating lymphocyte cell therapy, was approved in the United States on the basis of the pivotal C-144-01 study. A 5-year follow-up of the C-144-01 trial assessed the long-term efficacy and safety of lifileucel. At the cutoff date (November 20, 2024), the objective response rate was 31.4% (complete response [CR], 5.9%; partial response [PR], 25.5%). Overall, 79.3% of patients had tumor burden reduction; 16 had deepened responses with four converting from PR to CR > 1 year after lifileucel infusion; 31.3% of responders completed the 5-year assessment with ongoing responses. The median duration of response was 36.5 months. Responders (n = 48) had lower tumor burden and fewer liver or brain metastases than the overall population. The median overall survival (OS) was 13.9 months, with a 5-year OS of 19.7%. Adverse events were consistent with nonmyeloablative lymphodepletion and interleukin-2 safety profiles and declined rapidly within 2 weeks after lifileucel infusion. Most grade 3/4 cytopenias resolved to grade ≤2 by day 30. This 5-year analysis demonstrated long-term benefit and meaningful OS with one-time lifileucel therapy, with no additional long-term safety concerns.