<p>The aim of this study is to explore the differences in cortical activation and gait performance during turning walking under cognitive dual-task conditions between young and older adults during cognitive-turning dual task walking, as well as variations in brain functional connectivity in this context. Seventeen young adults and seventeen older adults were included in the study. All participants completed two tasks: a figure-eight turning walk (single-task, ST) and a figure-eight turning walking while performing a digital alert cognitive task (dual-task, DT). Data collection was conducted using functional near-infrared spectroscopy and a three-dimensional motion capture system to extract and calculate the activation of motor and sensory cortices, functional connectivity, and gait parameters. Compared to ST, the cortical activation in the young adults was significantly increased during DT (<i>p</i> ≤ 0.041) and was higher than that of the older adults (<i>p</i> ≤ 0.003); the older adults showed no significant change in cortical activation, and the stride length decreased (<i>p</i> = 0.013) and was lower than that of the young adults (<i>p</i> = 0.023). Additionally, compared to ST, the functional connectivity between primary somatosensory cortex and other brain regions increased in the older adults during DT (<i>p</i> ≤ 0.035). The older adults are more likely to fall when performing cognitive-turning DT. One of the important reasons for the difference between them and young adults is the distinct brain modulation mechanisms employed by the two groups when facing challenging dual tasks. Enhancing brain functional connectivity may be a more effective strategy for the older adults to promoting dual-task performance. This study provides insights for aging-related steering disorders and more evidence for the influence of aging on neuro-motor control mechanism.</p>