Following China's rapid socioeconomic transition, the sexual attitudes and behaviours of Chinese youth have changed considerably, raising serious concerns about their sexual and reproductive health (SRH). While comprehensive and high-quality formal sexuality education has been shown to lead to safer sexual behaviour, the delivery of formal SRH education in China remains insufficient, especially in Western regions. This study used qualitative approaches to evaluate the implementation of a live-streaming comprehensive sexuality education (CSE) programme in Western China between 2019 and 2021. Nineteen participants were recruited to participate in this study. Ten face-to-face, semi-structured interviews were conducted privately with specialists, school principals, and live-streaming tutors. Two focus groups were conducted with classroom teachers and junior secondary students, respectively. Findings reveal that both programme implementers and students demonstrated high satisfaction with CSE implementation. They indicated that CSE provision helped enhance adolescents' SRH knowledge and attitudes so as to better prepare them for a healthy and secure future. Findings demonstrate the effectiveness, efficiency, relevance, sustainability, and scale-up possibilities of the both the CSE curriculum and the live-streaming delivery approach. Findings may help guide future implementation of CSE at all levels, and thus improve access to CSE for vulnerable populations and diminish SRH disparities more effectively.