Insomnia is a common mental disorder with severe consequences. Cognitive-behavioral therapy for insomnia (CBTI) has been proved effective against insomnia, but most of the research is limited to Western countries. This trial objective is to develop a Chinese culture-adapted CBTI program and assess its efficacy. An 8-week culturally adapted CBTI program was developed that included mixed group and individual session and culturally adapted relaxation and cognitive restructuring treatment components. A one-arm clinical trial was conducted at a public hospital between March 2016 and January 2017. Seventy-two Chinese adults (15 males, 57 females; mean age, 50 years) with insomnia disorder underwent the culturally adapted CBTI program. Sleep diaries and self-report scales, as well as polysomnography (PSG, for a subgroup only), were used to assess qualitative and quantitative measures of sleep, mental health status, and quality of life at baseline, post-treatment, and 4-month follow-up. Pre-post analyses showed significant changes in sleep diary sleep onset latency (SOL), wake after sleep onset (WASO), and total sleep time of respectively - 37.03 min (CI, - 48.90 to - 25.16), - 28.16 min (CI, - 40.22 to - 16.10), and + 27.49 min (CI, 10.51 to 44.47). Self-reported sleep quality, mental health, and quality of life improved compared to baseline. The self-reported outcomes were mainly stable at follow-up. PSG outcomes globally failed to show improvement. The design of a CBTI program adapted to Chinese population was achieved. Culturally adapted CBTI showed promising results. More rigorously designed studies are needed to ensure efficacy.