To summarise existing systematic reviews which assessed the effects of physical exercise on activities of daily living, walking, balance and visual processing in people with dementia or mild cognitive impairment In this overview of systematic reviews and meta-analyses, seven electronic databases were searched to identify eligible reviews published between January 2015 and April 2021. A total of 30 systematic reviews were identified and included in the overview. The most frequent type of exercise for the intervention group was multimodal exercises. Mind-body exercises, exergames, dance intervention and aerobic exercise were other exercise types. Most of the reviews reported that exercise is significantly effective for improving activities of daily living (SMD 95%CI, from 0.27 to 1.44), walking (SMD 95%CI, from 0.08 to 2.23), balance (SMD 95%CI, from 0.37 to 2.24) and visuospatial function (SMD 95%CI, from 0.16 to 0.51), which are among the most leading determinants of independent living in individuals with dementia or mild cognitive impairment. Evidence has shown that exercise (especially multicomponent exercise programmes including cognitive, physical and multitasking exercises) with sufficient intensity improves the activities of daily living skills. Exercise also improves walking, balance and visual processing, which can provide a more independent life for people with dementia and mild cognitive impairment. Cognitively impaired people should therefore be encouraged to exercise regularly in order to be more independent. Supplemental data for this article is available online at http://dx.doi.org/10.1080/13607863.2021.2019192 [ABSTRACT FROM AUTHOR]