Transformational leadership (TFL) is often regarded as an ideal managerial approach, particularly in social work studies, where scholars have long examined its strong association with enhanced social workers' performance. However, recent research suggests that the effect of TFL may be overstated. This study investigates the relative importance of vertical TFL and horizontal workplace social capital (WSC) in predicting two key employee performance outcomes: organizational citizenship behavior and professional discretion (PD). It is proposed that the effects of both vertical and horizontal workplace relationships on performance may be moderated by organizational learning (OL). Drawing on survey data from Chinese public sector social workers (N = 815), the findings reveal that while TFL and WSC significantly enhance performance outcomes, supportive team relationships exert a comparatively more substantial effect than leadership. Furthermore, the analysis reveals that OL moderates the relationship between WSC and PD. These findings offer meaningful implications for the management of social service organizations and provide practical insights into strategies for improving social worker performance in public service settings. In the social work study, understanding what drives effective performance is crucial. Our latest research explores how leadership styles and team relations influence social worker outcomes in China's public sector. Although traditional leadership (transformational leadership) has been a focal point in past discussions, our findings suggest that high-quality workplace relationships (workplace social capital (WSC)) play a more pivotal role. Analyzing survey data from 815 public sector social workers, we discovered that while effective leadership does boost performance, the impact of strong, supportive team relationships is significantly greater. Moreover, our study highlights the importance of organizational learning, which moderates the relationship between WSC and professional discretion. This insight is particularly relevant for fostering effective practices within social service organizations, offering a fresh perspective on how to cultivate an environment that enhances the welfare and efficiency of both social workers and the communities they serve.