Prolonging overall survival (OS) remains an unmet need in relapsed or refractory multiple myeloma (RRMM). In ELOQUENT-2 (NCT01239797), elotuzumab plus lenalidomide/dexamethasone (ERd) significantly improved progression-free survival (PFS) versus lenalidomide/dexamethasone (Rd) in patients with RRMM and 1–3 prior lines of therapy (LoTs). We report results from the pre-planned final OS analysis after a minimum follow-up of 70.6 months, the longest reported for an antibody-based triplet in RRMM. Overall, 646 patients with RRMM and 1–3 prior LoTs were randomized 1:1 to ERd or Rd. PFS and overall response rate were co-primary endpoints. OS was a key secondary endpoint, with the final analysis planned after 427 deaths. ERd demonstrated a statistically significant 8.7-month improvement in OS versus Rd (median, 48.3 vs 39.6 months; hazard ratio, 0.82 [95.4% Cl, 0.68–1.00]; P = 0.0408 [less than allotted α of 0.046]), which was consistently observed across key predefined subgroups. No additional safety signals with ERd at extended follow-up were reported. ERd is the first antibody-based triplet regimen shown to significantly prolong OS in patients with RRMM and 1–3 prior LoTs. The magnitude of OS benefit was greatest among patients with adverse prognostic factors, including older age, ISS stage III, IMWG high-risk disease, and 2–3 prior LoTs.