Hip fractures are frequent injuries in older patients and are associated with high mortality rates. This study assessed the association between serum lactate level and 30-day mortality in older patients with unilateral hip fractures and examined the prognostic value of this association on the clinical outcomes of these patients. This retrospective, single-center study included patients aged ≥65 years admitted to the emergency department due to low-energy trauma and diagnosed with unilateral hip fracture upon admission. The additional inclusion criteria were patients with independent ambulation or walker or cane assistance before the injury, with available data on serum lactate levels on venous blood gas analysis, and who underwent surgery. Among the 330 included patients, 30.9% experienced postoperative complications and 10.3% died within 30 days. Using a lactate cut-off value of 2 mmol/L to distinguish between living and deceased patients, the sensitivity and specificity were 41% and 88%, respectively. Multivariate logistic regression analysis revealed that high lactate and low albumin levels and male sex were associated with mortality. Identifying risk factors for mortality in geriatric patients with hip fractures is important. Male sex, low albumin levels, and particularly increased lactate levels were independent predictors of short-term mortality in these patients.