Against the backdrop of accelerated government digital transformation, digital technologies are fundamentally reshaping civil servants’ work practices while simultaneously generating substantial technological pressure and adaptation challenges. Drawing on stress interaction theory and the job demands–resources model, this study develops and tests a double-edged sword framework to examine how digital transformation influences civil servants’ proactive service behavior. Using survey data from 583 Chinese civil servants and structural equation modeling, we find that digital transformation affects proactive service behavior through challenge technostress, while digital leadership positively moderates the relationship between digital transformation and challenge technostress. Furthermore, fuzzy-set qualitative comparative analysis (fsQCA) identifies three core conditions associated with high proactive service behavior: low hindrance technostress, high challenge technostress, and strong digital leadership. These findings underscore the critical role of perceived technological stress and contextual leadership in shaping proactive service behavior. This study contributes to the literature on digital governance and technostress by integrating variable-centered and configuration-based approaches, and it offers practical implications for enhancing civil servants’ adaptability and proactive service motivation in digitally transforming governments.