A triple-band miniaturized end-fire antenna based on the odd modes of spoof surface plasmonic polariton (SSPP) waveguide resonator is proposed in this paper. To meet the ever increasing demand for more communication channels and less antenna sizes, multi-band antennas are currently under intensive investigation. By a novel feeding method, three odd modes are excited on an SSPP waveguide resonator, which performs as an end-fire antenna operating at three bands, 7.15—7.26 GHz, 11.6—12.2 GHz and 13.5—13.64 GHz. It exhibits reasonably high and stable maximum gains of 5.26 dBi, 7.97 dBi and 10.1 dBi and maximum efficiencies of 64%, 92% and 98% at the three bands, respectively. Moreover, in the second band, the main beam angle shows a frequency dependence with a total scanning angle of 19°. The miniaturized triple-band antenna has a great potential in wireless communication systems, satellite communication and radar systems.