There is a tremendous progress in the design and synthesis of nano-scaled, non-viral carriers in the previous two decades. The nanodelivery systems can significantly improve biopharmaceutical features, pharmacokinetic properties and therapeutic efficacy of entrapped drugs. Branched polyethylenimine (PEI) is a cationic polymer that contains primary, secondary and tertiary amino groups. Such type of water-soluble polymer having high density of amines is one of the most promising cationic vectors for gene delivery. Hence, constructing nanocarriers that contain PEI have attracted much research effort in gene therapy because of the synergy effects of PEI molecules for their efficient transfection and the multi-functionality of nanoparticles in delivery. In this review, we focus on the recent development on the design and synthesis of four types of PEI-based nanocarriers: 1) PEI-based polymeric micelles systems; 2) PEI-based polymeric nanoparticle system; 3) PEI/silica nanoparticle systems; and 4) PEI/metal nanoparticle systems. Their in vitro gene transfaction and in vivo gene therapy will be also discussed. Results from these studies have demonstrated that PEI-based nanocarriers are promising delivery systems because of their efficient gene transfection, negligible toxicity, capability to co-deliver nucleic acids and chemotherapy drugs, ease of modification with the targeting molecules, and good responsiveness to external stimulus.