Recent studies have suggested that exposure to brominated flame retardants (BFR) may play a pivotal role in the development of high-fat diet-induced obesity and metabolic disorders in the liver. Ketone bodies produced by β-oxidation are utilized by acetoacetyl-CoA synthetase (AACS), a cytosolic ketone body-utilizing enzyme. Previously, we reported that the gene expression of AACS is upregulated in high-fat diet-induced obesity. Here, we examined the effects of BFR, tetrabromobisphenol A (TBBP-A), on gene expression in adipocyte cell line (ST-13). Treatment of differentiated cells with TBBP-A for 48 h did not have any remarkable effects on lipid accumulation and mRNA expression of AACS, PPAR-γ, SCOT, and FAS, whereas in undifferentiated cells, mRNA expression of for the lipid and ketone body utilizing-factors (AACS, perilipin-1, and FAS) and brown adipose tissue (BAT) related factors (UCPs, PRDM16, CIDEA, and LSD-1) was upregulated. These observations suggest that TBBP-A may dysregulate lipid metabolism in undifferentiated adipocytes during ketone body utilization via AACS.