Organic solar cells (OSCs) are an attractive technique for next-generation renewable energy. However, the intrinsically unstable nature of the organic compounds involved is delaying their commercialization. Therefore, it is essential to improve the lifetime of OSCs significantly. Here, we investigated the effect of the hydrophobic cyclized transparent optical polymer (CYTOP) as a solution-processable encapsulation layer based on shelf lifetime measurement, current–voltage characteristics, and impedance spectroscopy. We found that CYTOP utilization greatly enhanced OSCs’ shelf lifetime, maintaining 96% of initial performance when unencapsulated devices decreased to 82%. Furthermore, based on the dark current characteristics, ideality factor (n), and Cole–Cole plots, the CYTOP encapsulation is revealed to effectively inhibit unfavorable changes of parasitic resistive components and trap-assisted recombination. These findings provide an inclusive perspective on the shelf lifetime issue and commercialization of the OSCs.