PurposeAmbidextrous frontline service employees (FSEs), capable of delivering quality services and carrying out sales responsibilities too, are crucial to service firms. This study seeks to extend ambidexterity research by examining how a manager's goal orientation could influence FSEs' ambidextrous conversion. The authors draw on achievement goal theory and conceptualize a link between a manager's achievement goal orientation and employees' service–sales ambidexterity (SSA). The authors then apply conservation of resources theory to complement this high-level conceptualization, hypothesize mediating roles of important resources that can facilitate employees' SSA, and the authors test them empirically.Design/methodology/approachThis study adopts a questionnaire survey design. The empirical test relies on multilevel path analyses of dyadic data from 341 FSEs and 39 managers of a major logistics service company in Taiwan.FindingsManagers with a prominent learning goal orientation can facilitate and foster FSEs' SSA through developmental inducements and change-related self-efficacy, two important resources for their ambidextrous conversion. Managers with a strong performance-avoid goal orientation instead might hinder employees' SSA conversion, due to a negative impact on developmental inducements. Furthermore, SSA enhances FSEs' service delivery value and sales performance.Originality/valueBy analyzing and empirically testing the influence pathways of essential resources perceived by FSEs, which channel the effects of a manager's goal orientation to employees' SSA conversion, this study offers insights about how managers can support and foster FSEs' service–sales ambidextrous conversion.