Efficient delivery of small interfering RNA (siRNA) remains a challenging task in RNA interference (RNAi) studies. In this study, we used chitosan-graft-polyethylenimine (CHI-g-PEI) copolymer composed of chitosan and low molecular weight polyethylenimine (PEI) for the delivery of siRNA. The CHI-g-PEI carrier formed stable complexes with siRNA with compact spherical morphology. CHI-g-PEI delivered EGFP siRNA (siGFP) silenced EGFP expression nearly 2.5 folds higher than PEI25K at 50 pM siGFP concentration. Cell viability was found to be 2 folds high with CHI-g-PEI carrier than PEI25K. Also, our CHI-g-PEI carrier efficiently delivered Akt1 siRNA (siAkt) and thereby silenced onco-protein Akt1. Silencing of this crucial cell survival protein significantly reduced the lung cancer cell survival and proliferation. Additionally, Akt1 protein knock-down decreased A549 cell malignancy and metastasis. These findings suggest that the CHI-g-PEI carrier efficiently and safely delivered siRNA. Moreover, CHI-g-PEI mediated Akt1 siRNA delivery may emerge as a viable approach for lung cancer treatment.