In this article, the results of development, optimization, and analysis of new compact iris polarizers based on a square waveguide are presented. The polarization and matching characteristics of the polarizers with the different number of irises were optimized within the operating Ku-band 10.7-12.8 GHz. The numerical simulations and optimization of waveguide polarizer characteristics were carried out using a finite integration technique. The improvement of the performance of optimal polarizers and evolution of their dimensions was investigated for the polarizers with a number of irises ranging from 2 to 5. The best characteristics among the analyzed waveguide iris polarizers are achieved for the polarizer with 5 irises. Optimized compact square waveguide polarizer with 5 irises shows efficient polarization and matching performance in the whole operating Ku-band 10.7-12.8 GHz. Developed compact iris polarizers can be widely applied in modern dual-polarization antennas for satellite telecommunication systems.