This study aimed at achieving the molecular characterization of peroxisome proliferator-activated receptor-gamma coactivator 1β (PGC-1β) and exploring its modulatory roles in mitochondria biogenesis in blunt snout bream (). A full-length cDNA of was cloned from liver which covered 3110 bp encoding 859 amino acids. The conserved motifs of PGC-1β family proteins were gained by MEME software, and the phylogenetic analyses showed motif loss and rearrangement of in fish. The function of PGC-1β was evaluated through overexpression and knockdown of PGC-1β in primary hepatocytes of blunt snout bream. We observed overexpression of along with enhanced mitochondrial transcription factor A () expression and mtDNA copies in hepatocytes, and its knockdown led to slightly reduced expression. However, knockdown of PGC-1β did not significantly influence expression or mtDNA copies. The alterations in mitochondria biogenesis were assessed following high-fat intake, and the results showed that it induces downregulation of . Furthermore, significant decreases in mitochondrial respiratory chain activities and mitochondria biogenesis were observed by high-fat intake. Our findings demonstrated that overexpression of PGC-1β induces the enhancement of TFAM expression and mtDNA amount but not NRF-1. Therefore, it could be concluded that PGC-1β is involved in mitochondrial biogenesis in blunt snout bream but not through PGC-1β/NRF-1 pathway.