Single-photon avalanche diodes (SPADs), also referred to as Geiger-mode avalanche photodiodes, are primarily utilized in photon detection and counting. In this work, we present a measurement of the time-of-flight of minimum ionizing particles with outstanding timing resolution, achieved by using SPADs as direct particle detectors. We have measured the time-of-flight of 120 GeV/c momentum pions and achieved a coincidence time resolution of 15 ps full-width-at-half-maximum (FWHM) at system level.