Insomnia is an emerging risk factor for the onset of mild cognitive impairment (MCI) and its progression to dementia. Impaired cognition and neuropsychiatric symptoms create challenges for persons with MCI to participate actively in non-pharmacological interventions. This study examined the feasibility and preliminary effects of empowerment-based cognitive-behavioural therapy for insomnia (CBT-I) on sleep, cognitive function, and health-related quality of life (HRQoL) in persons with MCI and sleep problems. Sixty participants were randomly allocated to the intervention or control group to receive empowerment-based CBT-I or usual care, respectively. The 12 week intervention comprised all core CBT-I techniques delivered through a group and individualised face-to-face approach. An empowerment approach with interactive teaching methods, goal setting, and action planning was used to deliver the intervention. Outcome measures included subjective and objective sleep quality and pattern, and a battery of neuropsychological tests and the 12-item Short Form Survey were administered 3 months (T1) and 6 months post-randomisation (T2). This intervention is feasible and highly acceptable for persons with MCI. The intervention group showed significant improvements in subjective and objective sleep-related outcomes compared with the control group. Moreover, the intervention group showed greater improvements in global cognition, processing speed, attention, and mental flexibility than the control group at T1 and/or T2. No significant between-group differences were observed in memory or HRQoL scores. The qualitative data converged with the quantitative data. In conclusion, empowerment-based CBT-I was well received by persons with MCI and had potential positive effects on improving sleep and cognition in this cohort.