Lysozymes are essential enzymes in innate immunity, hydrolyzing bacterial cell walls. In Insecta, C-type and I-type lysozymes are conserved and play dual roles in immunity and digestion. Lysozyme gene dosage effects that are linked to copy number variation may influence their functional efficacy. This study investigates the distribution and evolution of lysozyme-like genes across Insecta. Genomes and protein files from 302 insect species were retrieved from the NCBI RefSeq database, maintaining the species with BUSCO above 90%. Alternative splicing isoforms were filtered using AGAT, retaining only the longest isoforms. Orthologous groups were identified using OrthoFinder and classified into C-type or I-type lysozymes through BLASTP and InterProScan analyses based on the predicted domains for the sequences. Phylogenetic reconstruction was performed with IQ-TREE using a constriction tree based on the literature, while gene family expansion/contraction events were analyzed using GeneRax. The conservation of active sites was evaluated via sequence alignment against the Gallus gallus C-type lysozyme (53-E; 70-D) and Crassostrea virginica I-type lysozyme (83-E; 94-D). Our analysis revealed 1,834 C-type and 886 I-type lysozyme-like sequences. Only 1,203 C-type sequences retained conserved active sites, with none being observed in Hymenoptera genomes, except for the groups Tenthredinoideam Ichneumonoidea and Vespoidea. Conversely, no Insecta I-type sequences exhibited conserved active sites. Phylogenetic reconciliation identified major duplication events during the Paleoptera–Neoptera split, with subsequent lineage-specific duplications and losses. Our results showed that Lysozyme-like genes exhibit significant variations in their copy number and sequence conservation across Insecta. The absence of conserved active sites in I-type sequences implies functional diversification beyond canonical muramidase activity; the absence of these sites in the majority of the Hymenoptera C-type lysozymes is otherwise potentially linked to taxon-specific adaptations, since several species of this group exhibit social immunity behavior. Our findings underscore the dynamic evolutionary history of lysozymes, highlighting their roles in immunity, digestion, and lineage-specific biological processes.