Palmitic acid-conjugated low molecular weight polyethylenimine (PEI-$g$-PEG-PA) was successfully synthesized to develop an efficient non-viral gene carrier. The judicious integration of hydrophobic palmitic acid and polyethylenimine $via$ hydrophilic polyethylene glycol (PEG) facilitated the formation of nano-sized complex (nanoplex) with plasmid DNA (pDNA) which provided the protection of pDNA against the serumic enzymatic degradation. Furthermore, the delivery system demonstrated enhanced gene transfection efficiency in comparison to unmodified low molecular weight PEI without inducing any significant cytotoxicity.