In this work, a new dual-band dielectric waveguide bandpass filter (BPF) based on 3D printable single spherical cavity is proposed for 5G wireless communication applications. By using two pairs of degenerate modes (i.e., TM 101 and TM 201 modes) in one single cavity, dual-band response can be constructed. The coaxial probes are set in the appropriate position to excite these operating modes and realize the reasonable control of the external coupling to achieve good return losses (RLs). In addition, high frequency selectivity is achieved by introducing source-to-load coupling. For verification, a dual-band prototype is designed and simulated.