Malnutrition (MN) is prevalent in older adults and closely related to sarcopenia, frailty, morbidity, mortality, and decreased quality of life. In this study, we aimed to evaluate the effects of a personalized diet combined with planned physical exercise on nutritional status, physical performance, and quality of life (QoL) in malnourished older adult patients. In this prospective study, 20 older adults with MN risk according to the Mini Nutritional Assessment-Short Form (MNA-SF) were randomized into (i) personalized diet (PD) and (ii) personalized diet with physical exercise (PDE) groups, and followed up with for 12 weeks. The physical exercise included warm-up, strengthening, balance, and cooldown phases, with a frequency of 3-4 days per week. Anthropometric measurements, physical performance, and quality of life were assessed using standardized tools at baseline and at the 4th, 8th, and 12th weeks. QoL was measured using the EQ-5D index and EQ-5D visual analog scale (VAS) scores. A total of 20 patients (55% male) participated in the study. During the study, BMIs, MNA-SF scores, and hand grip strength were increased, and the patients' average duration on the Timed Up and Go (TUG) test decreased significantly in both groups. The EQ-5D index score of the PD group and the EQ-5D VAS scores of both groups were increased. A personalized diet with or without physical exercise therapy was associated with improved nutritional status, physical performance, and QoL.