The goliath grouper (Perciformes: Epinephelidae) is a large, critically endangered fish distributed across coastal habitats in the western Atlantic Ocean, from Florida to southern Brazil, and with additional populations in the eastern Pacific basin. Conservation concerns for this species stem from historical overfishing, habitat loss, and life-history traits such as slow growth and late sexual maturity. In this study, to aid conservation efforts, we assembled and characterized the complete mitochondrial genome of . The mitochondrial genome of is 16,561 bp long and comprises 13 protein-coding genes (PCGs), two ribosomal RNA genes (12S and 16S rRNA), 22 transfer RNA (tRNA) genes, and an 856 bp control region. Gene order is identical to that reported for other congeneric species. The overall A + T content is 56%, and codon usage shows a preference for A + T-rich codons. All PCGs were found to be under purifying selection, with variation in selective pressure among genes; and were under the strongest and weakest selection, respectively. Secondary structure analysis of the tRNA genes displayed typical cloverleaf secondary structures, except for trnS1, which lacked a complete D-arm. Comparative analyses between MiTFi and RASP2 revealed that MiTFi provided more accurate predictions of tRNA secondary structures. The control region exhibited a high A + T content (69.9%), multiple microsatellite motifs, and one tandem repeat, along with hairpin secondary structures. These features mirror findings in closely related species. A maximum likelihood phylogenetic analysis based on translated PCGs did not support the monophyletic status of the genus and indicated a sister relationship between and , another large-bodied grouper from the Indo-Pacific Ocean. The newly sequenced mitochondrial genome of provides a new genomic resource that can support future conservation efforts.