Immunohistochemistry (IHC) and immunofluorescence (IF) are critical methods in cancer and immunology research, facilitating high-resolution analysis of protein distribution within tissue architecture. These techniques enable precise spatial mapping, and signaling pathway and cellular phenotype characterization in both normal and pathological states, offering powerful tools for investigating tumor cell-intrinsic biology, tumor microenvironment, and therapeutic responses. This chapter presents comprehensive and reproducible protocols for both chromogenic- and fluorescent-based immunodetection strategies in tissue sections with emphasis on methodological details and key considerations. Optimized for formalin-fixed, paraffin-embedded (FFPE) tissues, our protocols are compatible with a wide range of solid tumors and models, making them widely applicable for basic, translational, and clinical research.