Abstract2D magnetic semiconductors exhibit great potential for nextāgeneration spintronics, but realizing their full capabilities has been hindered by the low Curie temperatures (Tc) below 50 K observed in current materials. Here, a new mechanism to substantially enhance the Tc of 2D semiconducting materials through incorporating both ināplane and outāofāplane superexchange interactions enabled by structural design is demonstrated. Specifically, monolayer Cr2Se3 is synthesized with a fiveālayer SeāCrāSeāCrāSe atomic structure using molecular beam epitaxy (MBE). This unique structure not only possesses optimized ināplane superexchange interaction but also incorporates outāofāplane CrāSeāCr couplings. Scanning tunneling spectroscopy (STS) and angularāresolved photoemission spectroscopy (ARPES) confirm its semiconducting nature. Remarkably, the ferromagnetic phase transition observed by ARPES and Magnetic Force Microscopy (MFM) indicated that its Tc is up to 230 K. This not only establishes a new record for Tc in 2D ferromagnetic semiconductor materials but also introduces a novel approach to modulating materials' properties by manipulating the vertical dimension in 2D materials.