Background: The neutrophil-to-lymphocyte ratio (NLR) is an independent prognostic marker in solid and hematological cancers. While the derived NLR (dNLR) was shown to be non-inferior to the NLR in large cohorts of patients with different cancer types, it has not been validated as a prognostic marker for multiple myeloma (MM) to date. Methods: Between May 22, 2011 and May 29, 2014, 176 patients with MM from 38 centers who were ineligible for autologous stem cell transplantation were analyzed. The dNLR was calculated using complete blood count differential data. The optimal dNLR cut-off value according to receiver operating characteristic analysis of overall survival (OS) was 1.51. All patients were treated with melphalan and prednisone combined with bortezomib. Results: The complete response rate was lower in the high dNLR group compared to the low dNLR group (7 vs. 26.1%, respectively; p = 0.0148); the corresponding 2-year OS rates were 72.2 and 84.7%, respectively (p = 0.0354). A high dNLR was an independent poor prognostic factor for OS (hazard ratio 2.217, 95% CI 1.015–4.842; p = 0.0458). Conclusion: The dNLR is a readily available and cheaply obtained parameter in clinical studies, and shows considerable potential as a new prognostic marker for transplantation-ineligible patients with MM.