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Phosphoenolpyruvate carboxylase (PEPC) gene family plays a crucial role in both plant growth and response to abiotic stress. Approximately half of the Orchidaceae species are estimated to perform CAM pathway, and the availability of sequenced orchid genomes makes them ideal subjects for investigating the <i>PEPC</i> gene family in CAM plants. In this study, a total of 33 <i>PEPC</i> genes were identified across 15 orchids. Specifically, one <i>PEPC</i> gene was found in <i>Cymbidium goeringii</i> and <i>Platanthera guangdongensis</i>; two in <i>Apostasia shenzhenica</i>, <i>Dendrobium chrysotoxum</i>, <i>D. huoshanense</i>, <i>Gastrodia elata</i>, <i>G. menghaiensis</i>, <i>Phalaenopsis aphrodite</i>, <i>Ph. equestris</i>, and <i>Pl. zijinensis</i>; three in <i>C. ensifolium</i>, <i>C. sinense</i>, <i>D. catenatum</i>, <i>D. nobile</i>, and <i>Vanilla planifolia</i>. These <i>PEPC</i> genes were categorized into four subgroups, namely PEPC-i, PEPC-ii, and PEPC-iii (PTPC), and PEPC-iv (BTPC), supported by the comprehensive analyses of their physicochemical properties, motif, and gene structures. Remarkably, PEPC-iv contained a heretofore unreported orchid <i>PEPC</i> gene, identified as <i>VpPEPC4</i>. Differences in the number of <i>PEPC</i> homolog genes among these species were attributed to segmental duplication, whole-genome duplication (WGD), or gene loss events. <i>Cis</i>-elements identified in promoter regions were predominantly associated with light responsiveness, and circadian-related elements were observed in each PEPC-i and PEPC-ii gene. The expression levels of recruited BTPC, <i>VpPEPC4</i>, exhibited a lower expression level than other <i>VpPEPC</i>s in the tested tissues. The expression analyses and RT-qPCR results revealed diverse expression patterns in orchid <i>PEPC</i> genes. Duplicated genes exhibited distinct expression patterns, suggesting functional divergence. This study offered a comprehensive analysis to unveil the evolution and function of <i>PEPC</i> genes in Orchidaceae.