BACKGROUND: Patients with Parkinson's disease (PD) receiving device-aided therapies (DATs) frequently experience vitamin B depletion and nutritional challenges. However, the effects of continuous subcutaneous apomorphine infusion (CSAI) on vitamin B status and nutritional outcomes in advanced PD remain unclear. OBJECTIVE: To evaluate the clinical effectiveness of CSAI and associated changes in vitamin B status, homocysteine (Hcy) levels and nutritional outcomes in patients with advanced PD. DESIGN: A prospective observational cohort study in a single centre. METHODS: Thirty patients with advanced PD were enrolled between January 2023 and March 2025. Clinical, biochemical and nutritional assessments were performed at baseline and after 3 months. Motor outcomes included daily OFF hours, dyskinesia hours, Hoehn and Yahr stage and the Unified PD Rating Scale (UPDRS). Biochemical measures comprised serum vitamins B1, B6, B12, folate and plasma Hcy levels. Nutritional status was assessed using body weight, body mass index (BMI) and the Mini Nutritional Assessment-Short Form (MNA-SF). RESULTS: Thirty participants (mean age 68.5 ± 9.2 years; disease duration 12.0 ± 3.9 years; Hoehn & Yahr 3.7 ± 0.7) completed follow-up. After 3 months of CSAI, daily OFF hours, dyskinesia hours and UPDRS Part 4 scores decreased significantly (p < 0.05 for all). The oral levodopa daily dose was significantly reduced (p < 0.001). Serum vitamin B1 and B12 levels increased significantly, while Hcy levels showed a modest but significant reduction (p < 0.05). Body weight, BMI and total MNA-SF score remained unchanged (p > 0.05). However, MNA-SF categories shifted toward improved nutritional classification (p = 0.008). Adjunctive antiparkinsonian medications were significantly reduced, while levodopa remained universally prescribed. CONCLUSION: CSAI significantly reduced motor complications and oral levodopa exposure. Secondary analyses showed selective biochemical improvements with stable overall nutritional status. Findings should be interpreted considering the observational design, lack of control group and short follow-up.