PIWI-interacting RNAs (piRNAs), an emergent type of non-coding RNAs during oncogenesis, play critical roles in regulating tumor microenvironment. Systematic analysis of piRNAs' roles in modulating immune pathways is important for tumor immunotherapy. In this study, in-depth analysis of piRNAs was performed to develop an integrated computational algorithm, the immunology piRNA (ImmPI) pipeline, for uncovering the global expression landscape of piRNAs and identifying their regulatory roles in immune pathways. The immunology piRNAs show a tendency towards overexpression patterns in immune cells, causing perturbations in tumors, being significantly associated with infiltration of immune cells, and having prognostic value. The ImmPI score can contribute to prioritizing tumor-related piRNAs and distinguish two subtypes of SKCM (immune-cold and hot phenotypes), as characterized by different prognoses, immunogenicity and antitumor immunity. Finally, we developed an interactive web resource (ImmPI portal: http://www.hbpding.com/ImmPi) for the biomedical research community, with several useful modules to browse, visualize, and download the results of immunology piRNAs analysis. Overall, our work provides a comprehensive landscape of piRNAs across multiple cancer types and sheds light on their regulatory and functional roles in tumor immunity. These findings pave the way for future research and development of piRNA-based immunotherapies for cancer treatment.