Miniaturization of device elements, such as ferroelectric diodes, depends on the downscaling of ferroelectric film, which is also crucial for developing high‐density information storage technologies of ferroelectric random access memories (FeRAMs). Recently emerged ferroelectric two‐dimensional (2D) van der Waals (vdWs) layered materials bring an additional opportunity to further increase the density of FeRAMs. A lateral, switchable rectifier is designed and fabricated based on atomically thin 2D α‐In2Se3 ferroelectric diodes, thus breaking the thickness limitation of conventional ferroelectric films and achieving an unprecedented level of miniaturization. This is realized through the interrelated coupling between out‐of‐plane and in‐plane dipoles at room temperature; that is, horizontal polarization reversal can be effectively controlled through a vertical electric field. Being further explored as a switchable rectifier, the obtained maximum value of rectification ratio for the α‐In2Se3 based ferroelectric diode can reach up to 2.5 × 103. These results indicate that 2D ferroelectric semiconductors can offer a pathway to develop next‐generation multifunctional electronics.