Organizational culture is widely recognized as an important contextual factor shaping career development and long-term human resource sustainability. Although prior research has examined organizational culture, career development, and sustainable HRM, these constructs have often been studied separately and predominantly within Western contexts. This study addresses this gap by analyzing their interrelationships within a transitional economy. Grounded in sustainable human resource management and sustainable careers perspectives, the study examines how organizational culture typologies influence career development and HR sustainability. Career development is operationalized through organizational career growth and career competences. Survey data were collected from 542 employees across 23 IT and manufacturing companies in Serbia and analyzed using factor analysis and multiple regression. The findings show that organizational culture significantly shapes career growth opportunities and career competences and is also directly related to HR sustainability. Person-oriented cultures are associated with more favorable career development conditions and higher levels of HR sustainability, while power- and role-oriented cultures are linked to weaker outcomes. Career growth and career competences further emerge as key mechanisms supporting long-term workforce sustainability. This study contributes to the literature by integrating organizational culture, career development, and HR sustainability into a single analytical framework within a transitional economy context and provides practical insights for managers aiming to foster sustainable careers and long-term HR sustainability.