This letter presents a novel ultrawideband (UWB) bidirectional transmit-reflect-array (TRA) antenna with dual-polarized characteristics. The proposed TRA antenna, which combines reflectarray antennas (RAs) and transmitarray antennas (TAs), can achieve y-polarization transmission and x-polarization reflection. The two polarizations can be independently controlled and share the same UWB frequency band. The TRA achieves a bandwidth of more than 5:1 (2.8 to 15.2 GHz) by using tightly coupled modified dipole (TCMD) radiators. To validate this design concept, a prototype of the proposed TRA comprising 24 × 24 elements is designed, fabricated, and measured. With no distortion for both the RA and TA modes within the operating band, the experimental results show a peak gain of 24.9 dBi and 25 dBi, and a peak aperture efficiency of 38% and 39% for the RA and TA modes, respectively. The measurement and simulation results agree well, indicating potential applications in 6G bidirectional communication.