Background: The clinical significance of serum potassium levels at admission in patients with blunt hepatic trauma remains insufficiently defined. This study aimed to evaluate the prevalence and prognostic value of admission hypokalemia in this patient population. Methods: We conducted a retrospective analysis of 164 patients with radiologically confirmed blunt liver trauma admitted between 2016 and 2023. Preoperative, intraoperative, and postoperative data were collected to assess the association between serum potassium levels and trauma severity (AAST grade—American Association for the Surgery of Trauma, ISS—Injury Severity Score), in-hospital morbidity, mortality, and length of stay. Univariate and multivariate analyses were performed, including checks for normality and multicollinearity. Results: Serum potassium levels showed a significant positive correlation with age (p = 0.0064), and an inverse correlation with liver injury severity (AAST grade; p = 0.01). Lower potassium levels were associated with longer hospital stays (p = 0.0459) and higher morbidity (p = 0.022). In multivariate analysis, only age (p = 0.036) and AAST grade (p = 0.014) were independent predictors of serum potassium concentration. Potassium levels were not independently associated with mortality. Conclusions: Admission hypokalemia is a common finding in blunt liver trauma and correlates with injury severity and adverse clinical outcomes. Potassium concentration may serve as a readily available, low-cost biomarker for early risk stratification in these patients. Further prospective studies are warranted to confirm its prognostic utility.