Abstract: The present study involves the preparation, characterization, and evaluation of novel alginate nanocarrier for sunitinib (STB), an anticancer drug. Sunitinib (STB) is a weakly soluble drug in water due to its poor dissolution rate and oral bioavailability. Alginate biopolymer is one of the promising candidates for a delivery matrix. A controlled gelification method using calcium chloride as the crosslinker was done for the formulation of STB using nanoalginate. The objective of this work was to evaluate the physicochemical/biological properties of the release system via in vitro dissolution studies and cytotoxicity studies. The bare alginate nanoparticles and STB-loaded alginate nanoparticles were characterized for its physicochemical properties using FT-IR, SEM, and TEM studies. The formulation and loading chemistry were well exhibited by FTIR analysis results. SEM and TEM results revealed the spherical and rod-like shape morphology with rough surface where the drug molecules were adhered. The entrapment efficiency and dissolution studies of the drug were done through UV VIS instrument. In vitro cytotoxic studies were performed for loaded sunitinib alginate biopolymer (STB-AL-NPs). The cytotoxicity results reveal that the cytotoxicity is mainly due to the loaded anticancer drug sunitinib. Lay Summary: In this study, sunitinib drug was encapsulated in alginate nanoparticles effectively. The interaction between polymer, crosslinker, and drug was well determined using FTIR, XRD, SEM, TEM, and Zeta potential. The results are compared with bare alginate nanoparticles. The expected entrapment efficiency of the drug carrier was around 99% via UV-Vis spectroscopy, proving good drug-polymer interaction. In vitro drug release studied was done by dissolution method using 900 mL of 0.2 mM PBS, to determine the sustained release of the drug from the excipient. The results proved that the drug was released to the medium in the sustained manner. Future Scope: Sunitinib-encapsulated alginate nanoparticles not only offer several advantages over conventional drug therapies but also expected to overcome the side effect regarding to dosing and toxicity while administration. However, further optimization studies includes stabilization and targeting should be performed for both in vitro and in vivo.