Background Cognitive frailty is defined as the presence of both physical frailty and cognitive impairment (clinical dementia rating score = 0.5), in the absence of dementia. It is characterized by concurrent physical frailty and potentially reversible cognitive impairment. In this study, we sought to elucidate the effects of high-speed resistance exercise training on cognitive function and physical performance in older adults with cognitive frailty. Methods We conducted a parallel-group, randomized controlled trial involving community-living older adults with cognitive frailty. The participants’ mean age was 73.9 (± 4.3 SD) years, and 69.8% (n=30) were female. Two different 4-month interventions included high-speed resistance exercise training group (n=22) and a control group (balance and band stretching, n=23). Frailty score, cognitive function (memory, processing speed, cognitive flexibility, working memory, executive function), physical function (SPPB, TUG, gait speed), and muscle strength (grip strength, knee extension strength) were assessed at baseline, 8 weeks, and 16 weeks. Results Statistical analysis showed that exercise improved performance significantly in the tests for cognitive function (processing speed and executive function, both p < 0.05), physical function (SPPB, TUG, gait speed, both p < 0.05), and muscle strength (grip strength, knee extension strength, both p < 0.05). However, no significant changes in frailty score were observed between intervention and either control group (p < 0.05). Conclusion In conclusion, our findings indicate that high-speed resistance exercise training approaches are effective in improving cognitive function and physical performance in older adults with cognitive frailty. This study shows that it is feasible to identify older adults with cognitive frailty in the community and primary care setting for effective intervention to reduce their level of frailty and cognitive impairment.