Quantum-dot-sensitized solar cells (QDSSCs) usually suffer from a strong recombination effect or low stability, resulting in a low efficiency and limiting their practical application. A facile liquid-phase synthesis of anti-monene quantum dots (AMQDs) with unique morphology and size distribution is demonstrated, and applied as an effective photoactive material in QDSSCs for the first time. The intrinsic advantages of AMQDs, in association with a strong light-matter interaction, moderate energy band-gap in the visible range and antioxidation properties, enable an impressive photoelectric conversion efficiency (PCE) to be obtained, where the hysteresis-free AMQD-based solar cells can reach up to 3.07%. Furthermore, the as-fabricated solar cell shows a long-term stability, where the PCE value maintains to more than 90% of the initial value after 1000 h. In view of highly cost-effective synthesis and outstanding photoelectrochemical performance, we anticipate that AMQDs will have a promising future in solar cells and related photonics applications. AMQDs may provide a new direction for the rapidly developing photovoltaic technology, which is necessary for further developments in this field.