Objectives In a randomised controlled trial, we investigated whether a cognitive training based on rhythm–music and music improvisation exercises had positive effects on executive functions in older participants. Methods Thirty‐five residents in a guest home with mild–moderate cognitive impairment and healthy ageing were randomly assigned to an experimental group (n = 18) featuring cognitive music training composed of 12 bi‐weekly 70‐min sessions, and a control group (n = 17) attended 12 bi‐weekly 45‐min sessions of gymnastic activities offered by the institute. A neuropsychological test battery was administered at baseline and at the end of treatment, including the Mini‐Mental State Examination, verbal fluency test, Trail Making Test A, attentional matrices test and clock‐drawing test. Results Pre‐test and post‐test comparison showed a significant improvement for the experimental group reflected in the Mini‐Mental State Examination (F(1,33) = 13.906; p < 0.001; pη2 = 0.296), verbal fluency test (VFL) (F(1,33) = 6.816; p < 0.013; pη2 = 0.171), and clock‐drawing test (F(1,29) = 16.744; p < 0.001; pη2 = 0.366), while the control group did not show any significant improvements. In addition, there was a tendency towards significance for the Trail Making Test A (F(1,20) = 3.268; p < 0.086; pη2 = 0.140). Regarding the attentional matrices test, no significant differences were found for the experimental group (F(1,29) = 2.833; p < 0.103; pη2 = 0.089), while the control group had a significant performance reduction (F(1,29) = 3.947; p < 0.050; pη2 = 0.120). Conclusion The use of a cognitive protocol based on music‐rhythmic exercises and music improvisation exercises is associated with improved cognitive functions in older people with mild–moderate cognitive impairment regardless of the individual's degree of cognitive reserve. Copyright © 2017 John Wiley & Sons, Ltd.