The anticancer potential of gemcitabine, a nucleoside analog, is compromised due to the enzymatic degradation into inactive form leading to the short half-life in systemic circulation. Novel delivery strategies are required to improve therapeutic efficacy of this potential drug. Monomethoxy polyethylene glycol amine-polylactide-co-glycolide (mPEG-PLGA) co-polymer was synthesized and characterized by FTIR and 1H NMR. Gemcitabine loaded mPEG-PLGA nanoparticles (NPs) were developed and investigated for pharmacokinetic profile and in vivo anticancer activity. The mPEG-PLGA NPs (size: 267 ± 10 nm, zeta potential: − 17.5 ± 0.2 mV) exhibited sustained drug release profile and were found to be compatible with blood. The mPEG-PLGA NPs were able to evade the uptake by macrophages (i.e. THP-1 and J774A) by reducing the adsorption of proteins on the surface of NPs. The enhanced cellular uptake and cell cytotoxicity was observed by mPEG-PLGA NPs in MiaPaCa-2 and MCF-7 cells. The half-life of gemcitabine in mPEG-PLGA NPs was remarkably enhanced (19 folds) than native gemcitabine. Further, the pharmacokinetic modulation of gemcitabine using mPEG-PLGA-NPs was translated in improved anticancer efficacy as compared to native gemcitabine in Ehrlich ascites bearing Balb-c mice. The results demonstrated the potential of long-circulatory nanoparticles in improving the pharmacokinetic profile and in-turn the anticancer efficacy of gemcitabine.