Context: Hypericum perforatum L., commonly known as St. John's wort, is practised as an alternative medicine against depression. Conversely, its remedial efficacy is indulged by various adverse effects that are recuperated in formulating nanoscaled commercial capsules encased by the biopolymer chitosan. A potential application of nanoencapsulation with regards to polymer enhances a slow controlled release of the targeted drug to achieve the desired delay until the right stimulus is obtained. Aims: To value synthesizing biopolymeric nanocomposites encapsulating St. John's wort commercial capsules substantiating it with a study of animal model of depression to endorse the effect of nanocapsulated drug as an effective brain drug. Methods The nanoparticulated suspension was prepared by ionic gelation technique and characterized to attest its antidepressant activity by in vivo studies. Results: The drug binding efficiency was endorsed by FT-IR studies and the nanoparticles were characterized by an average particle size of 211.4 nm with a positive zeta potential of 45.9 mV. The animal despair studies on depression induced mice models displayed a significant difference in the immobility time during force swimming and tail suspension test. The commercial capsules were administed orally (p.o., 50 and 100 mg/kg). The animal despair studies were substantiated with affirmative biochemical assessments like SOD, CAT, GP(x), GSH and LPO and compared with control groups. Conclusions: The outcomes of this work manifest the calibre of St. John's wort nanocomposites in a lower dosage that can alleviate depression and reduce side effects.