The effect of dietary inulin on the intestinal bacterial communities of Penaeus vannamei by 16S metagenomic analysis was assessed. PCR amplified the V3 region of the bacterial 16S rDNA. Sequencing reads were generated using the 2×150 (300 cycles) for the base-read length chemistry of the Illumina MiniSeq platform. The software Shaman and MicrobiomeAnalyst were used to analyze the sequences. The phylum Proteobacteria and the genus Vibrio were among the most abundant taxonomic ranks for control and inulin treatment. The relative abundance of the phylum Bacteroidetes and genus Ruegeria was lower in inulin treatment concerning the control condition. Alpha and beta indices did not show significant differences between inulin treatment and control conditions. For all samples, most of the bacterial organisms showed the presence of carbohydrate and amino acid metabolism-related genes, and to a lesser extent, of energy, lipid, and cofactors and vitamin metabolism-related genes. The principal metabolic functions were glycine, serine, threonine, glyoxylate and dicarboxylate, purine, pyrimidine, pyruvate, and quorum sensing. The interaction network analysis showed fewer interactions in the inulin treatment concerning control condition. Proteobacteria, Bacteroidetes, Vibrio, and Ruegeria predominated in all samples, and inulin did not change the net microbial diversity in the intestine of P. vannamei. Streptomyces, Roseobacter, and Ruegeria showed negative interactions with Vibrio, suggesting their use as probiotics. This study sheds light on the inulin supplement on the essential role of microbiota in the shrimp.