Optical bistability can be used to explore key components of all-optical information processing systems, such as optical switches and optical random memories. The hybrid integration of emerged two-dimensional layered PtSe₂ with waveguides is promising for the applications. We demonstrated the optical bistability in the PtSe₂-on-silicon nitride microring resonator induced by a thermo-optic effect. The fabricated device has a resonance-increasing rate of 6.8 pm/mW with increasing optical power. We also established a theoretical model to explain the observation and analyze the device’s performance. The study is expected to provide a new scheme for realizing all-optical logic devices in next-generation information processing systems.