Mitochondrial protein p13 is a less understood protein possibly related to cardiac pathophysiology. Since mice lacking the p13 (p13-/- mice) showed markedly reduced white adipose tissue (WAT) weight, this study explores the roles of p13 in WAT in vivo, in silico and in vitro. Histological analysis revealed a marked difference in WAT rather than heart and brown adipose tissue (BAT) of p13-/- mice, in which significant decreases in adipocyte and lipid droplet size were observed. Quantitative mRNA expression analysis showed p13-/- WAT exhibited decreasing tendencies of a mature adipocyte marker aP2, and of adipogenesis-related transcription factor C/EBPs. Several in silico analysis indicated that p13 can be targeted by several transcription factors and miRNAs related to adipocyte development. Finally, we observed transient increase of p13 expression in the murine 3T3-L1 adipocyte cell differentiation model. Collectively, these data suggest possible roles of endogenous p13 in the development of white adipocyte tissue.