<p>Workplace well-being is strongly influenced by interpersonal relationships, although less is known about whether the benefits of high-quality workplace ties vary across demographic characteristics. This study examines whether employee age and gender moderate the relationship between the quality of relationships with supervisors and coworkers and affective–relational workplace well-being. Using data from the Sixth European Working Conditions Survey and Partial Least Squares Structural Equation Modeling, the results show that both supervisor and coworker relationships are positively and significantly associated with workplace well-being, with a slightly stronger effect for hierarchical relationships. Moderation analyses indicate that age weakens these associations, suggesting that relational quality is more relevant for younger employees. No significant moderating effect of gender is observed, which may suggest that the relationship under study tends to be similar for men and women in this context. These findings contribute to the literature by integrating relational and lifespan perspectives to explain how workplace relationships influence well-being across the career span. From a practical perspective, the results highlight the importance of designing age-sensitive interventions, particularly at early career stages, while suggesting that core relational conditions such as support, fairness, and cooperation are broadly relevant across gender groups.</p>