This study investigated the effects of 12-week interventions on cognitive and physical fitness adaptations in older men with cognitive decline. We employed a randomized, parallel, and controlled design with five groups: team sports (TS), team sports with cognitive training (TS+C), aerobic exercise (A), aerobic exercise with cognitive training (A+C), and a control group (Control). Fifty older male volunteers (mean age: 69.3 ± 3.2 years) were included in the analysis. Interventions consisted of two 60-minute sessions per week for 12 weeks. Both TS and A groups participated in structured physical training, with TS involving 5v5 handball and football games, and A focusing on circuit training exercises. The TS+C and A+C groups additionally incorporated 20-minute cognitive training sessions using a software, targeting memory, attention, and executive functions. The control group maintained their usual routines. Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA). Physical fitness was assessed through six tests of the Senior Fitness Test. Results revealed significant post-intervention differences in MoCA (p < 0.001, ηp² = 0.622), chair stand (p = 0.038, ηp² = 0.189), up and go (p < 0.001, ηp² = 0.516), and 6-minute walk test (p = 0.001, ηp² = 0.333) scores among groups. Post hoc analysis showed that TS, TS+C, A, and A+C groups significantly improved in MoCA, chair stand, up and go, and 6-minute walk test compared to the control group (p < 0.05). No significant differences were observed for arm curl, sit and reach, or back scratch tests. Our findings suggest that 12-week interventions incorporating team sports or aerobic exercise, with or without cognitive training, can improve cognitive function and physical fitness in older men with cognitive decline, and may contribute to strategies aimed at promoting healthy aging.