Background: Immune checkpoint inhibitors (ICIs) combined with platinum-based dual chemotherapy has been widely used as first-line treatment modality for patients with locally advanced or metastatic non-small cell lung cancer (NSCLC). This study aimed to investigate the potential value of lactate dehydrogenase to albumin ratio (LAR) in predicting treatment efficacy in these patients. Methods: A total of 110 patients with locally advanced or metastatic NSCLC treated with first-line chemoimmunotherapy between January 2021 and March 2024 at Xuanwu Hospital, Capital Medical University, were enrolled. In different subgroups, according to a 50% ratio, patients were divided into high baseline LAR and low baseline LAR groups and their progression-free survival (PFS) was compared. Then univariate and multivariate cox hazard analyses were conducted to identify independent predictors of PFS. Finally, a nomogram was constructed to intuitively show the results. Results: The PFS of patients with high baseline LAR was significantly shorter than that of patients with low baseline LAR, regardless of whether in the overall patient population, different staging subgroups, or different pathological type subgroups (P<0.01). Based on multivariate cox analysis, age, programmed deathligand 1 (PD-L1) tumor proportion score (TPS) and baseline LAR were identified as independent indicators affecting PFS. Then a nomogram based on these three predictors was constructed accordingly and its C-index was 0.801 [95% confidence interval (CI): 0.747-0.855]. Conclusions: The present study demonstrates that LAR is a useful prognostic predictor in patients with locally advanced or metastatic NSCLC treated with first-line chemoimmunotherapy in clinical practice.