Purpose: At present, there is a controversy regarding the effect of dual-task training on improving the cognitive function of people with mild cognitive impairment (MCI). This study was to develop and verify the effects of the cognitive–physical dual-task training program on the executive function of older adults with MCI. Method: Participants were randomly allocated to the experimental group (EG) receiving cognitive–physical dual-task training (n = 21) or the control group (CG) receiving cognitive single-task training (n = 21). Results: After 16 sessions for 8 weeks, the Korean version of the Executive Function Performance Task (EFPT-K), the Frontal Assessment Battery (FAB), and Korean version of the Instrumental Activities of Daily Living (K-IADL) tests were implemented to assess people’s executive function and instrumental activities during daily living. As the result, there were no significant differences in general characteristics between both groups (p> 0.05). After 16 sessions, the EG showed greater improvements in the EFPT-K (p< 0.05; η2= 0.133), the FAB (p< 0.001; η2= 0.305), and the K-IADL (p< 0.01; η2= 0.221) compared to those of the CG. Conclusion: These results indicate that cognitive–physical dual-task training is clinically beneficial to improve the executive function and daily instrumental activities of older adults with MCI. Cognitive–physical dual-task training is a promising intervention for older adults with MCI.