Spermiogenesis defines the final phase of male germ cell differentiation. Multiple deubiquitinating enzymes have been linked to spermiogenesis, yet the impacts of deubiquitination on spermiogenesis remain poorly characterized. Here, we investigated the function of UAF1 in mouse spermiogenesis and male fertility. We selectively deleted Uaf1 in premeiotic germ cells using Stra8-Cre knock-in mouse strain (Uaf1 sKO), and found that Uaf1 is essential for spermiogenesis and male fertility. We found that UAF1 interacts and colocalizes with USP1 in testes. Conditional knockout of Uaf1 in testes results in disturbed expression and localization of USP1, suggesting that UAF1 regulates spermiogenesis through the function of the deubiquitinating enzyme USP1. We used tandem mass tag-based proteomics to identify differentially expressed proteins and potential underlying mechanisms, and found that conditional knockout Uaf1 in testes results in reduced levels of proteins essential for spermiogenesis. Thus, the UAF1/USP1 deubiquitinase complex is essential for normal spermiogenesis by regulating the levels of spermiogenesis-related proteins.