This study reports the successful growth of large-area ultraflat chiral blue phosphorene (BlueP) on a copper (Cu) surface using molecular beam epitaxy (MBE). BlueP, a theoretically proposed phosphorous allotrope with a buckled honeycomb lattice, has attracted significant interest due to its intriguing properties. The researchers discovered that the BlueP grown on Cu exhibits an ultraflat honeycomb lattice, characterized by strong stretching and rotational stacking with the substrate, leading to the formation of a highly ordered spatial chirality. This chiral structure is confirmed through geometric phase analysis (GPA) and scanning tunneling microscopy (STM). Spectroscopic measurements, including scanning tunneling spectroscopy (STS) and field-emission resonance (FER) spectroscopy, reveal that the ultraflat chiral BlueP is metallic and exhibits different characteristic quantum oscillations in the image-potential states, indicating distinct local work functions (LWFs) between the chiral units. The study also demonstrates a reversible transformation between chiral and achiral phases, suggesting a unique growth mode for phosphorene structures. These findings open up new possibilities for applications in polarization optics, spintronics, and chiral catalysis.This study reports the successful growth of large-area ultraflat chiral blue phosphorene (BlueP) on a copper (Cu) surface using molecular beam epitaxy (MBE). BlueP, a theoretically proposed phosphorous allotrope with a buckled honeycomb lattice, has attracted significant interest due to its intriguing properties. The researchers discovered that the BlueP grown on Cu exhibits an ultraflat honeycomb lattice, characterized by strong stretching and rotational stacking with the substrate, leading to the formation of a highly ordered spatial chirality. This chiral structure is confirmed through geometric phase analysis (GPA) and scanning tunneling microscopy (STM). Spectroscopic measurements, including scanning tunneling spectroscopy (STS) and field-emission resonance (FER) spectroscopy, reveal that the ultraflat chiral BlueP is metallic and exhibits different characteristic quantum oscillations in the image-potential states, indicating distinct local work functions (LWFs) between the chiral units. The study also demonstrates a reversible transformation between chiral and achiral phases, suggesting a unique growth mode for phosphorene structures. These findings open up new possibilities for applications in polarization optics, spintronics, and chiral catalysis.