This book chapter examines the concepts of workplace loneliness and social capital management from an organizational behavior perspective, addressing their increasing significance in organizations amid digitalization and the proliferation of flexible work arrangements. Workplace loneliness is defined as a subjective psychological state arising from the perceived discrepancy between desired and actual social relationships in the work environment. This phenomenon is analyzed through two fundamental dimensions: emotional and social loneliness. Social capital is evaluated through its structural, relational, and cognitive dimensions as a fundamental resource supporting trust, reciprocity, and sense of belonging within organizations. The study emphasizes that workplace loneliness tends to be lower in organizations with strong social capital, whereas persistent loneliness leads to the erosion of social capital over time. Within this bidirectional relationship framework, teamwork, mentoring systems, organizational socialization processes, and leadership approaches that foster psychological safety are proposed as strategic tools for preventing workplace loneliness. In this context, the conscious and systematic management of social capital is considered a critical managerial tool for enhancing employee well-being and sustaining organizational success.