It is always an active research field to search for materials with high catalytic efficiency, and good electrochemical activity and stability to construct electrochemical sensing platform. This work developed a hollow-structure porphyrin zirconium-based MOF (HPCN-222) as support of single Pt atoms to prepare the single-atom catalysts (SACs) PtHPCN-222. The high specific surface area of HPCN-222 provided a large number of anchoring sites for immobilizing single Pt atoms and maximized their atomic utilization. The strong interaction between the support (HPCN-222) and Pt atom made single Pt atom disperse stably, and changed the electronic structure of Pt atom, thus enabling SACs PtHPCN-222 to achieve high catalytic efficiency and good electrochemical activity and stability. With levodopa as model target, the SACs PtHPCN-222 modified electrode (PtHPCN-222/GCE) was constructed to explore its high catalytic efficiency for biomolecules. It was demonstrated that PtHPCN-222/GCE has satisfactory selectivity and reasonable reproducibility for the detection of levodopa. Two linear ranges were obtained and they were 0.1–1.0 μM (R² = 0.999) and 1–130 μM (R² = 0.997). The detection limit was 3 nM (S/N = 3) and the sensitivity was 0.1066 μA⋅μM⁻¹. Furthermore, the PtHPCN-222/GCE has reasonable recovery for the analysis of levodopa in human serum and extreme stability after being stored at 4 °C for 150 days, thus providing a highly efficient single-atom catalytic platform for bioanalysis.