Objective: We investigated the possible association between lower serum lactate to albumin ratio upon hospital arrival and out-of-hospital cardiac arrest (OHCA) outcome. Methods: Records from the Japanese Association for Acute Medicine–Out-of-Hospital Cardiac Arrest (JAAM-OHCA) Registry were used for this multicenter observational study. Enrolled patients were ≥18 years old with OHCA of medical etiology who were hospitalized after spontaneous circulation returned between June 1, 2014, and December 31, 2021. We excluded those with missing data or those who failed to meet predefined inclusion criteria. The primary outcome was a cerebral performance category scale of 1 or 2 which indicated 30-day survival with favorable neurological outcome. Patients were divided into quartiles based on serum lactate to albumin ratios. The multivariable logistic regression analysis included adjustment for multiple factors. Results: Data from 4,413 patients were analyzed. The primary outcome was achieved by 558 of 1,104 patients (50.5%) in the first quartile (lactate to albumin ratio, ≤2.23), 240 of 1,111 patients (21.6%) in the second quartile (lactate to albumin ratio >2.23–3.39), 96 of 1,096 patients (8.8%) in the third quartile (lactate to albumin ratio >3.39–4.70), and 24 of 1,102 patients (2.2%) in the fourth quartile (lactate to albumin ratio, >4.70). Adjusted odds ratios (95% confidence intervals) for the primary outcome in the second, third, and fourth quartile compared with the first quartile were 0.33 (0.26–0.42), 0.19 (0.14–0.26), and 0.07 (0.04–0.11), respectively. Conclusion A statistically significant association between categorization in the lower lactate to albumin ratio quartile group and favorable neurological outcome after OHCA was identified.