This communication introduces a dual-polarized filtering antenna designed for base station systems, featuring a broad impedance bandwidth and high selectivity. For the first time, high-impedance lines are introduced to create a radiation null, effectively suppressing unwanted radiation in the target frequency band. Additionally, a novel parasitic structure is presented to enhance the impedance bandwidth of dual-polarized antennas. By combining these two innovative techniques with the multipath coupling method, a broadband dual-polarized filtering antenna is successfully realized. The proposed design was fabricated and tested to validate its performance, with measured results closely matching the simulations. These results demonstrate that the antenna achieves a wide impedance bandwidth of 47.8% (1.67–2.72 GHz) and high out-of-band rejection level. The peak in-band gain is 9.4 dBi. These advantages make it an excellent candidate for integrated base station systems.