Abstract A transmitarray adopting dual‐layer polarisation rotating (PR) elements is proposed. The element comprises a pair of perpendicularly placed C‐shaped slots etched on the two sides of a single‐layer substrate and orthogonally rotates transmission wave polarisation with regard to the incidence. By adjusting C‐shaped slot's dimension as well as mirroring the bottom layer of the element, a 360° phase shift with a high transmission magnitude is achieved. Based on the proposed unit‐cell, a dual‐layer transmitarray composed of 529 elements is designed and developed. The experimental 1‐dB gain bandwidth and peak aperture efficiency are 13% and 44% respectively. Furthermore, sidelobe level of 20 dB and cross polarisation level of 26 dB are obtained at 10 GHz. These promising properties demonstrate the superiority of the element for transmitarray designs. In addition, this element can be also a good candidate for folded transmitarray designs.