Background: In the peripheral blood, the neutrophil–lymphocyte ratio (NLR) and platelet–lymphocyte ratio (PLR) change in response to malignancy. These biomarkers are associated with adverse outcomes in numerous cancers, but the evidence is limited in relation to melanoma. This study sought to investigate the association between these biomarkers and survival in Stages I–III cutaneous melanoma. Methods: This multicenter cohort study investigated a consecutive series of patients who underwent wide excision of biopsy-proven cutaneous melanoma and sentinel lymph node biopsy during a 10-year period. The baseline NLR and PLR were calculated immediately before sentinel lymph node biopsy. Adjusted hazard ratios (HRs) for overall and melanoma-specific survival were generated. Results ;Overall, 1351 patients were included in the study. During surveillance, 184 of these patients died (14%), with 141 of the deaths (77%) attributable to melanoma. Worse overall survival was associated with a baseline NLR lower than 2.5 [HR 2.2; 95% confidence interval (CI) 2.0 to 2.3; p < 0.001] and a baseline PLR lower than 100 (HR 1.8; 95% CI 1.7 to 1.8; p < 0.001). Melanoma-specific survival also was worse, with a baseline NLR lower than 2.5 (HR 1.9; 95% CI 1.6 to 2.2; p < 0.001) and a baseline PLR lower than 100 (HR 1.9; 95% CI 1.7 to 2.2; p < 0.001). The 5-year survival for patients with sentinel lymph node metastases and a low NLR and PLR was approximately 50%. Conclusion: This study provides important new data on biomarkers in early-stage melanoma, which contrast with biomarker profiles in advanced disease. These biomarkers may represent the host inflammatory response to melanoma and therefore could help select patients for adjuvant therapy and enhanced surveillance.