Objectives: The International Classification of Functioning, Disability and Health (ICF) is a framework providing information on disability and health. Physical activity's behavior is complex and affected by various factors. We aimed to examine the ICF domains in Parkinson's disease (PD) patients; to compare them in sedentary and non-sedentary PD patients and their association with activity level. Patients and Methods: Sixty PD patients (25 sedentary PD group, 35 non-sedentary PD group) were included in this retrospective study. Functional disability was evaluated using the Movement Disorder Society Unified Parkinson's Disease Rating Scale. The physical activity level was measured by the SenseWear Arm Band activity monitor. Patients’ cognitive function, severity of depression and anxiety, the functional impact of fatigue, balance performance (NeuroCom Balance Master System), functional mobility (Timed Up and Go Test, TUG), walking capacity (Six-Minute Walk Test, 6MWT), fear of falling, health-related quality of life are also analyzed. Results: Sedentary PD patients had worse scores in NeuroCom Balance Master System parameters, TUG score, and 6MWT distance in activities domains of the ICF model as a guide than non-sedentary group (p < 0.05). No statistically significant differences were found in the body structures and function, participation, personal and environmental domains of the ICF model between sedentary and non-sedentary PD groups (p > 0.05). There was no correlation between steps taken per day and NeuroCom Balance Master System parameters, TUG score, and 6MWT distance in both groups (p > 0.05). Conclusion: Patients with sedentary lifestyle had worse scores in postural control/balance, sit-to-stand and walking performance. However, deteriorated dynamic balance may not lead to sedentary lifestyle. Physiotherapy programs should be including the behavior change interventions and motivational strategies to promote activity level in PD.