A broadband dual circularly polarized (DCP) filtering dielectric patch antenna (DPA) is proposed in this letter. Firstly, based on the coupling topology of a bandpass filter, the filtering response of the DPA is designed using its first two resonant modes (TM101 and TM121). Accordingly, the theoretical external quality factors are derived from the synthesized coupling matrix and are physically realized by constructing an air cavity and tuning the slot length. Subsequently, the four microstrip feedlines are replaced with two hybrid couplers to realize the DCP function. In order to study the isolation between the DCP ports, an anisotropic DP model is established, and an improvement scheme of isolation is provided. For demonstration, a prototype is designed, fabricated and measured. The proposed DPA shows a wide effective DCP bandwidth of 23.5% from 4.29 GHz to 5.43 GHz, which is the overlapped bandwidth of the −10 dB return loss, −15 dB DCP isolation, 3 dB axial ratio (AR), and 1 dB gain. Besides, the proposed DPA achieves a peak CP gain of 8.3 dBi with a low profile of 0.055λ₀.