A compact triple-mode dielectric resonator (DR) bandpass filter (BPF) based on a single waveguide cavity is proposed, while three resonant modes of a single cavity are classified as a TM mode and a pair of hybrid degenerate modes (HE modes). Two HE degeneration modes in a single metal cavity are excited by using an off-centered DR approach. They work together to constitute a three-pole passband with a fractional bandwidth of 2.7% at the central frequency of 2.53 GHz. To verify the proposed idea, the proposed triple-mode DR BPF is fabricated by using silver plated aluminum metal cavity, and the simulated and measured results are in good agreement.