Background: Community-acquired pneumonia (CAP) is a leading respiratory related illness causing significant morbidity and mortality worldwide. Serum lactate is an important marker of tissue hypoperfusion and metabolic stress. It is used now increasingly as the potential marker for prognosis. The current study aimed to determine the prognostic value of serum lactate as a marker in adult patients with CAP. Methods: This prospective observational study was conducted in 40 adult patients (≥18 years) admitted with CAP at a tertiary care hospital. A thorough clinical examination, laboratory, and radiological assessment were made in each case.  The estimation of serum lactate was taken at the time of admission. Clinical outcomes were assessed in terms of the length of hospital stay, the need to be admitted to the intensive care unit (ICU), and in-hospital mortality. Analysis of data by appropriate statistical tests was carried out, and the correlation between serum lactate and outcomes was ascertained. Results: Of the 40 patients, 24 (60%) had elevated serum lactate (>2 mmol/L). Patients with higher lactate levels had significantly increased disease severity, longer mean hospital stay (9.2 ± 2.4 vs. 5.6 ± 1.8 days; p<0.01), higher ICU admission rates (45.8% vs. 12.5%; p=0.02), and greater mortality (20.8% vs. 0%; p=0.03) compared to those with normal lactate. Elevated lactate was an independent predictor of poor outcomes after adjusting for age and comorbidities. Conclusion: Our study found that serum lactate can be a simple, rapid, and reliable biomarker for prognosis in adult CAP patients. Incorporating lactate measurement in the routine evaluation of suspected CAP cases can enhance early risk stratification and guide ICU referrals if needed, and help in optimal resource utilization.