OBJECTIVE: People with Parkinson's disease (PwPD) experience a gradual decline in bed mobility independence as the disease progresses. Identifying factors associated with nonindependence in daytime bed mobility is crucial for developing effective interventions to increase independence. We investigated factors associated with nonindependence in daytime bed mobility in PwPD. METHODS: This cross-sectional study included 109 PwPD (Hoehn and Yahr [HY] stage 2-4). Patients' bed mobility ability (turning in bed, supine-to-sitting, and sitting-to-supine) was assessed during the daytime, and they were categorized into independent and nonindependent groups. Potential factors associated with bed mobility independence, including components of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (rigidity, bradykinesia, tremor, axial symptoms), neck/trunk/hip strength, the Mini-Mental State Examination, and the Trail Making Test-A and B, were evaluated. RESULTS: The nonindependent group presented significantly increased axial symptoms, increased rigidity in the upper and lower limbs and neck, increased upper limb bradykinesia, and decreased trunk flexion/extension strength in all bed mobility tasks (p<0.05). Multivariate regression analyses revealed that axial symptoms, upper limb rigidity, and trunk extension strength were highly discriminative for nonindependence in turning in bed (the area under the curve [AUC]=0.84). Similarly, upper limb rigidity and axial symptoms were predictive of nonindependence in supine-to-sitting and sitting-to-supine movements (AUC=0.78, 0.92). A significant difference in axial symptoms between the HY stage 4 subgroups was observed only in the sitting-to-supine movement. CONCLUSION: Our findings indicate that axial symptoms and upper limb rigidity are key factors contributing to nonindependence in daytime bed mobility tasks among PwPD. Targeting these factors in rehabilitation may help mitigate the decline in bed mobility independence in PwPD.