2D ferroelectrics provide great promise for future electronics owing to their unique properties at 2D limit. Although simple perovskite oxides(such as BaTiO3 and PbTiO3) are an important target for 2D ferroelectrics, controlled synthesis of 2D nanosheets still remain a challenge. Here, thisissue is addressed by using a new chemical protocol; unilamellar Ti<>sub0.87O2 nanosheets can serve as templates, guiding the solvothermal synthesis of2D BaTiO3 nanosheets with a molecularly thin thickness (< 3 nm). Raman spectroscopy, second harmonic generation, and transmission electron microscopy characterizations suggest the formation of tetragonal ferroelectric BaTiO3 nanosheets. Based on piezoresponse force microscopy, BaTiO3 nanosheets exhibit a clear ferroelectric response with a high Curie temperature (≈100 °C) even down to 1.8 nm thickness. This study provides new opportunities to investigate perovskite ferroelectrics with the critical thickness.