The stability of perovskite quantum dot solar cells is one of the key challenges of this technology. This study reveals the unique degradation behavior of cesium lead triiodide (CsPbI₃) quantum dot solar cells. For the first time, it is shown that the oxygen-induced degradation and performance loss of CsPbI₃ quantum dot photovoltaic devices can be reversed by exposing the degraded samples to humidity, allowing the performance to recover and even surpass the initial performance. By careful characterization and analysis throughout the degradation and recovery process, the underlying physical and chemical mechanisms that govern the evolution of the device performance could be identified. It is shown that the ligand shell of the quantum dots, rather than the instability of the semiconducting material itself, is the driving factor in these mechanisms. This highlights the important role of surface chemistry and ligand design in enhancing perovskite quantum dot photovoltaics.