Abstract Using crafted microstructures with complex molecular ordering has proven to be an excellent approach to control the propagation and phase front of light, and consequently, has led to remarkable advances in various photonic devices. A polarization‐conversion‐type polarizer with extraordinarily high transmittance can be another innovative photonic application that can be realized using microfabricated molecular ordering; however, the technology is still at the stage of idea generation. Here, a novel polarization conversion polarizer is demonstrated using a polymerized liquid crystalline double microprism (DMP) array and patterned retarder. A lab‐made polarizer using the method exhibits the degree of polarization of 94.5% without absorption or large reflection of light, and its transmittance is found to be ≈1.8 times higher than a dichroic sheet polarizer. In addition, the DMP polarizer works in the full spectral range of visible light and its thickness is less than 150 µm; therefore, it can be used in flat photonic devices, including displays. DMP polarizers can easily be fabricated using well‐established soft lithography and photoalignment methods. Thus, the proposed technology can open new possibilities for polymerized liquid crystal films with well‐crafted molecular ordering.