We investigated the spectral characteristics of whispering gallery mode (WGM) lasing in semiconductor square microcavities with various corner shapes. For a simple square cavity, the lasing spectrum showed a complex peak pattern with a broad envelope due to lasing of multi-spatial WGMs. In order to reduce the number of lasing modes, we proposed and fabricated hollow square cavities with symmetric concave-shaped corners. The lasing peaks appeared as periodic narrow peaks corresponding to closed WGMs due to the strong mode selection roles of proposed geometry. If the corner geometry was modified to form 45$^circ$-tilted and convex shapes, ring-type WGMs originating from total reflection of light at the four corners could be selectively lased.