Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor (resting tremor, rigidity, bradykinesia, postural instability, and gait disturbances) and nonmotor symptoms (cognitive, neuropsychiatric, and autonomic problems). In recent years, several studies demonstrated that neurorehabilitation therapy is an effective treatment in addition to pharmacological personalized interventions in persons with PD (PwPD). The main aim of this study was to explore the short-term changes in functional, cognitive, and geriatric domains after a multidimensional rehabilitation program in PwPD (as primary condition) in mild–moderate (M-Ms) to severe (Ss) stages. Our second aim was to compare the effects of multidimensional rehabilitation in M-Ms versus Ss of PD. Twenty-four PwPD in M-Ms to Ss [age (mean ± SD) = 76.25 ± 9.42 years; male/female = 10/14; Hoehn and Yahr (median; IQR) = 4.00; 1.75] were included in a retrospective, observational study. Motor, cognitive, functional, and neuropsychiatric aspects were collected in admission (T0) and in discharge (T1). PwPD were involved in a person-tailored (to individual's needs), inpatient, intensive (5–7 days per week), multidisciplinary (combining cognitive, physical, occupational, and speech therapies), comprehensive, and rehabilitative program. According to Movement Disorders Society Unified Parkinson's Disease Rating Scale III cutoff, PwPD were classified in M-Ms or Ss (M-Ms ≤59; Ss >59); 87.50% of our sample reported significant reduction of functional disability at Barthel Index (p < 0.001). A significant improvement in Token test (p = 0.021), semantic fluency (p = 0.036), Rey's Figure-Copy (p < 0.001), and Raven's Colored Progressive Matrices (p = 0.004) was observed. The pain intensity perception (p < 0.001) and the risk of developing pressure ulcers (p < 0.001) as assessed, respectively, by the Numeric Rating Scale and by the Norton Scale were improved. With regard to the second aim, in M-Ms group, we found a positive correlation between the number of neuromotor sessions and the change in functional disability and language comprehension; in the Ss group, on the other hand, despite a higher number of hospitalization days, the total number of completed sessions was positively associated with the change in visuoconstructional abilities. Our findings suggest that an intensive, inpatient, and multidisciplinary rehabilitation program may improve functional abilities, some strategic cognitive functions, and geriatric aspects in PwPD with mild–moderate motor impairment.