Design thinking, an approach traditionally used to develop or improve products, services, or processes within design and engineering sectors, has emerged as a novel pedagogical approach. As design thinking becomes more widely established within education contexts, it is important to gain deeper insight as to how such learning environments operate. The aim of this study was to explore online design thinking through the lens of psychological safety. We used a qualitative single-case study design to investigate nine students' experiences across a nine-week design-thinking project. Data were collected via semi-structured interviews and reflective journal entries, and analysed through reflexive thematic analysis. Our findings suggested that psychological safety is a valuable consideration in the design and implementation of online design-thinking learning environments. Facilitators of psychological safety included having collaborative environments, encouraging leadership, and a focus on team formation. Barriers to psychological safety included difficulties connecting, fear of speaking, and cultural considerations. Our findings also highlighted several outcomes of psychologically safe team climates, including creativity, collaboration, and the development of approaches to working with uncertainty.