This study aimed to evaluate the impact of rehabilitation through serious games on range of motion (ROM), flexibility, muscular endurance, and cognition in an elderly volunteer with a history of reduced mobility and mild cognitive decline. An experimental case study was conducted at the volunteer's residence. The participant, diagnosed with bilateral bursitis and reduced shoulder ROM, and mild cognitive decline, was subjected to an intervention protocol based on serious games. Physical and cognitive assessments were conducted before and after the implementation of the protocol, including measurements of range of motion (goniometry), flexibility (sit and reach test), endurance (elbow flexion test), and cognition (tests to evaluate cognitive abilities and reaction time). The intervention consisted of 8 sessions over 4 weeks, with sessions lasting 20 min each, conducted twice a week. After the intervention with serious games, significant improvements were observed in shoulder range of motion, with notable gains in flexion, adduction, abduction, internal rotation, and external rotation. Additionally, there were improvements in flexibility, muscular endurance with a substantial increase in the number of elbow flexions, and cognitive abilities, with a decrease in reaction time. The results of this study are consistent with previous research highlighting the effectiveness of technological approaches in rehabilitation. It is concluded that the use of serious games as part of the intervention protocol proved effective in improving the range of motion and cognition of a patient with reduced mobility and mild cognitive decline. This study provided evidence of the potential of serious games as an innovative therapeutic approach in physical and cognitive rehabilitation.