Background and Objective: Individuals with Alzheimer disease and dementia experience cognitive decline and reduction in physical capabilities. Engaging in cognitive challenges and physical exercises is effective in reducing age-related cognitive and physical decline. It is believed that physical activity in the context of cognitive challenges might enhance the process of neurogenesis in the adult brain, but how effective are such interventions? Is there enough evidence to support that dual-task training is more effective than cognitive or physical training alone? To what extent can such training improve cognitive and physical functions in patients at various stages of cognitive decline? Methodology: This systematic review with meta-analysis summarizes the emerging evidence of dual-task training for enhancing cognitive and physical functions in older individuals with cognitive impairment, dementia or Alzheimer’s disease. A systematic search was carried out in MEDLINE, PubMed, EMBASE, and Cochrane Library with the following search terms: randomized control trials, dual-task training, SCD, MCI, dementia, and Alzheimer’s disease. Results: A total of 21 studies with 2,221 participants were identified. The results of dual-task tanning intervention are summarized as change in global cognitive function; SMD = 0.24, (P= 0.002), memory; SMD = 0.28, (P = 0.000), executive function; SMD = 0.35, (P = 0.000), attention; SMD = −0.19, (P = 0.1), gait speed; SMD = 0.26, (P = 0.007), dual-task cost; SMD 0.56, (P = 0.000), and balance; SMD 0.36, (P = 0.004). Conclusion: Primary analysis showed a small-to-medium positive effect of dual-task training interventions on cognitive functions and medium-to-large positive effect on gait functions and balance.