In this study, we investigate the effects of patent applications on corporate bond ratings of Korean listed firms. Using an ordered probit regression, we show that firms with higher patent counts and greater patents to R&D investments are likely to have significantly higher bond ratings. This finding remains robust while considering the differences of firms with patenting versus without patenting, and adopting alternative variables measured by industry-adjusted numbers of patent applications. We further explore two possible channels through which patent applications affect corporate bond ratings. First, patent applications provide expectations for increased cash flows with debt market. Second, patent applications enable improved redeployability of assets held by firms. Through a series of analyses, this study sheds lights on the real effects of patenting activities on the debt market via firms’ bond ratings.