Introduction: Lymphomas encompass over 80 malignancies defined by morphology, Immunohistochemistry (IHC), molecular, and genetic features in the 2022 WHO classification. IHC remains central for lineage determination, proliferative assessment, and therapeutic targeting. However, immunophenotypic data from Malaysia are limited. Methods: We conducted a retrospective study of 398 mature lymphomas diagnosed in a tertiary hospital (2015–2022) with adequate IHC reports. Sixty immunomarkers were analysed. Results: Pan-B cell markers (CD20, CD79a) were strongly expressed across B-cell lymphomas but absent in T-cell and NK/T-cell neoplasms. BCL2 was frequent in indolent B-cell variants but absent in Burkitt lymphoma, while BCL6 and CD10 highlighted germinal centre–derived subtypes. MUM1 was enriched in activated B-cell type DLBCL, high-grade B-cell lymphomas, and Hodgkin lymphoma. CD30 and PAX5 reliably identified classical Hodgkin lymphoma, and Cyclin D1 confirmed mantle cell lymphoma. Among 177 DLBCL cases, immunophenotypic variation was observed between germinal centre, activated B-cell, and non-GCB subtypes, with co-expression of BCL2, BCL6, and C-MYC in high-grade B-cell lymphoma suggestive of double/triple-hit biology. Ki-67 indices were ?70% in 72% of assessed cases, emphasising the high proliferative burden of aggressive subtypes. Expression patterns also differed between nodal and extranodal presentations, reflecting clinical heterogeneity. Conclusions: This first large-scale audit of lymphoma immunophenotypes in Malaysia demonstrates broad concordance with international data while providing novel local insights. The findings reinforce the diagnostic and prognostic value of IHC in refining classification and guiding precision-based lymphoma management.