Background/Objectives: Combining exercise with cognitive training (Combined Intervention) is a strategy against age-related cognitive decline; however, the best exercise type to maximize the neuroprotective effects of combined intervention remains unclear. Therefore, this systematic review and meta-analysis (SRMA) aimed to compare the effects of combined interventions (exercise plus cognitive training) versus exercise-only on cognitive function and blood biomarkers in older persons across different exercise types. Methods: PubMed, Scopus, PsycInfo, and Web of Science databases were searched without time restriction. Study quality was evaluated using a modified Downs and Black checklist. Extracted data were analyzed using the random-effects model with Comprehensive Meta-Analysis 4.0 software. Results: Twenty-four studies involving 1079 participants (mean age 72.97 ± 5.55 years), with and without mild cognitive impairment (MCI), were included in the present SRMA. Overall, combined interventions demonstrated a small but significant effect size (ES) of 0.335 (95% CI: 0.212 to 0.459; p < 0.001) on cognitive function compared to exercise alone. When categorized by exercise type, significant additional cognitive benefits were observed for aerobic (ES = 0.382; p < 0.001), multicomponent (ES = 0.261; p = 0.005), and resistance exercise (ES = 0.440; p = 0.005) combined with cognitive training compared to exercise alone. However, combined interventions showed no significant additional effect on BDNF levels (ES = 0.457; 95% CI: −0.896 to 1.809; p = 0.508). Conclusions: Incorporating cognitive training into an exercise program showed small but significant additional benefits to overall cognitive function in older persons compared with physical exercise alone. However, the results should be interpreted with caution due to existing limitations.