E-learning has been proposed as a sustainable delivery method for higher education. During the COVID-19 pandemic, online/e-service-learning was widely adopted around the world as a replacement for face-to-face service learning, providing an opportunity to explore whether e-learning as a sustainable delivery method could be applied to service learning. The present study adopted a qualitative approach to investigate the e-service-learning experiences of Mainland Chinese students studying at a Hong Kong university with regard to their general perceptions about the e-service-learning projects, perceived learning gains, and factors associated with their learning gains. A total of 28 undergraduates who participated in e-service-learning in the 2020/21 academic year were recruited from different faculties of the university. Seven focus groups were established with the participants. The results showed that Mainland Chinese students generally had positive perceptions about their experiences in e-service-learning during the pandemic. They appreciated the convenient and effective online learning and service, although they needed contact that is more direct with service recipients to deepen their reflection. Students perceived that they had improved their problem-solving skills and subject knowledge; they also gained meaningful personal growth and positive emotions through e-service-learning. Facilitators of and barriers to students' effective learning were also identified. The findings provide important evidence for the effectiveness of e-service-learning from the perspective of Mainland Chinese students at Hong Kong universities and the potential of e-service-learning as a sustainable delivery method for service-learning programs in the post-pandemic era. Copyright ©2023 Mdpi.