Photoblinking and photobleaching are commonly encountered problems for single-photon sources. Numerous methods have been devised to suppress these two impediments; however, either the preparation procedures or the operating conditions are relatively harsh, making them difficult to apply to practical applications. Here, we reported giant suppression of both photoblinking and photobleaching of a single fluorescent molecule, terrylene, via the utilization of hexagonal boron nitride (h-BN) flakes as substrates. Experimentally, a much-prolonged survival time of terrylene has been determined, which can have a photostable emission over 2 h at room temperature under ambient atmospheres. Compared with single molecules on a SiO2/Si substrate or glass coverslip, a more than 100-fold increase in the total number of photons collected from each terrylene on h-BN flakes has been demonstrated. We also proved that the photostability of terrylene molecules can be well maintained for more than 6 months even under ambient conditions without any further protection. Our results demonstrate that the utilization of h-BN flakes to suppress photoblinking and photobleaching of fluorescent molecules has promising applications in the production of high-quality single-photon sources at room temperature.