Aim: The aim of this study is to determine the effect of a 20-week Physical Activity Program for elderly individuals with mild cognitive impairment (MCI) on their cognitive functions and sleep quality. Methods: A randomized controlled trial research design was used in this experimental pretest-posttest study. The data were analyzed using SPSS 21.0. Results: This study showed that the Physical Activity Program improved the cognitive functions and sleep quality of elderly individuals (p < 0.05). Conclusion and Practice Implications: The findings of this study showed that the cognitive functions and sleep quality of elderly individuals improved thanks to a 20-week Physical Activity Program. It is recommended that physical activities should be included in nursing interventions for elderly people with MCI.