Background: Workplace loneliness affects employees’ emotional distress and job performance yet validated measurement tools for Korean workers remain limited. This study aims to translate and validate the Loneliness at Work Scale (LAWS) into Korean. Methods: LAWS was translated according to international guidelines as follows: forward translation, reconciliation, back translation and review, and cognitive debriefing. For validation, 1,000 full-time Korean employees proportionally distributed across sex, age, and occupational type were surveyed in November 2024 with a four-week follow-up (N = 200). Internal consistency and test—retest reliability were examined. The validity of the measure was tested by correlational analyses and confirmatory factor analysis. Results: LAWS-K demonstrated excellent internal consistency (Cronbach α overall = 0.936, emotional deprivation = 0.933, social companionship = 0.902) and satisfactory test—retest reliability (r = 0.780).The confirmatory factor analysis revealed that the revised two-factor model provided the best fit (comparative fit index = 0.916, Tucker—Lewis index = 0.897, root mean square error of approximation = 0.126, standardized root mean square residual = 0.045). Correlations with the SingleItem Workplace Loneliness Question (r = 0.612) and the Three-Item Loneliness Scale at Work (r = 0.682) demonstrated strong criterion validity. Correlations with occupational stress (r = 0.531), psychological distress (r = 0.543), work performance (r = -0.337), engagement (r = -0.462), and wellbeing (r = -0.490) supported convergent validity. Conclusion LAWS-K adapted for the Republic of Korea demonstrated robust reliability and validity. It provides Korean researchers and practitioners with a validated tool for assessing workplace loneliness, enabling targeted interventions and research initiatives to address this occupational health concern.