Dhatryadi Rasayana revitalizes the human body and helps in maintaining health with the elimination of ill effects of various diseases. The effective delivery systems for Rasayana may affect the profound effect of active principles in the body. The present study deals with investigation and evaluation of phytochemical constituents, physicochemical characteristics, along with antioxidant and immunomodulatory effects of Dhatryadi Rasayana in churna (powder) and granule formulations. Dhatryadi Rasayana churna and its granules were studied for various physicochemical parameters, e.g., moisture content, ash-value, acid-insoluble ash content, water-soluble extractive, alcohol-soluble extractive, bulk density, tapped density, angle of repose, Carr's index, Hausner's ratio, total sugar, reducing sugar, non-reducing sugar, heavy metals, total microbial load, etc. In vitro antioxidant potential of Dhatryadi Rasayana churna and its granules was determined by scavenging the DPPH and FRAP assays. The immunomodulatory activities of Dhatryadi Rasayana churna and its granules were studied in Wistar albino rats and the complete blood count (CBC), delayed-type hypersensitivity reaction (DTH), and hemagglutination antibody titer were assessed. Dhatryadi Rasayana churna contained alkaloids (0.50 ± 0.298% w/w), tannins (9.84 ± 1.527% w/w), saponins (4.18 ± 2.126% w/w), and flavonoids (9.34 ± 1.026% w/w), while its granules contained 11.08 ± 2.468% w/w total tannins, 2.40 ± 1.132% w/w alkaloids, and 12.46 ± 2.645% w/w total flavonoids. The DPPH scavenging effect was determined by IC50 (churna - 23.89 μg/mL; granules - 9.33 μg/mL), and the antioxidant capacity assessed by FRAP was 77.0 mmol/100 g equivalent of ascorbic acid for churna and 50 mmol/100 g equivalent of ascorbic acid for granules. Dhatryadi Rasayana churna and its granules reflected a significant immunostimulatory effect on both the cell-mediated and humoral immune systems in Wistar albino rats. Moreover, churna and granules of Dhatryadi Rasayana revealed significant antioxidant and immunomodulatory activities and these may be applied for treating different diseases as well as improving the immunity of the body.