While knowledge transfer (KT) is often studied in terms of its antecedents and barriers, less attention has been paid on its outcomes for scientists. Drawing on survey data from 1,909 biotechnology and health scientists affiliated with German universities, universities of applied sciences, and public research organizations, we analyze the effects of four distinct KT activities, cooperative knowledge development, knowledge and technology dissemination, technology transfer, and personnel transfer, on job satisfaction. This study explores the dual role of KT, offering both opportunities and challenges for scientists, and examines how Psychological Capital (PsyCap) moderates these effects. The findings reveal that KT engagement has non-linear effects on job satisfaction, with PsyCap playing a critical role in enhancing satisfaction and mitigating potential downsides. These insights contribute to the literature by emphasizing the need for balanced KT strategies and highlighting PsyCap as an important resource for sustaining scientists’ job satisfaction.