Lipid droplets (LDs) represent specialized cell organelles for the storage of energy rich lipids. Although lipid storage is a conserved feature of all cells and organisms, only little is known about fundamental aspects of the cell biology of LDs, including their biogenesis, structural assembly and subcellular positioning, and the regulation of organismic energy homeostasis.We identified a novel LD-associated protein family, represented by the Drosophila protein CG9186 and its murine homolog MGI:1916082. In the absence of LDs, both proteins localize at the endoplasmic reticulum (ER). Upon lipid storage induction, they translocate to LDs using an evolutionary conserved targeting mechanism that acts via a 60 amino acids targeting motif in the center of the CG9186 protein. Overexpression of CG9186 and MGI:1916082 causes clustering of LDs in both tissue culture and salivary gland cells, whereas the RNAi knockdown results in a reduction of LDs. Organismal RNAi knock-down of CG9186 results in a reduction of the lipid storage levels of the fly. The results indicate that we identified the first members of a novel and evolutionary conserved family of lipid storage regulators, which are also required to properly position LDs within cells.