The present study was designed to assess the effects of Cassia siamea leaf extract-mediated silver nanoparticles treatment on the fertility potential of male albino Wistar rats, to check their contraceptive efficacy. This plant is being traditionally used for various therapeutic purposes, including treating fever, skin diseases, hypertension, insomnia, diabetes, and asthma, as well as other pharmacological activities such as antimicrobial, antifertility, antioxidant, and analgesic properties. For this purpose, nanoparticles of the plant leaves were synthesized and characterized by different techniques as UV-Vis spectroscopic analysis, EDS, and DLS analysis. The animals were divided equally into five treatment groups, drug of 10, 20, and 30 mg/kg body weight per day was administered orally for 60 days, including group-I as control (vehicle treated) and group-V was kept at 30-day recovery period. A significant change in the reproductive organ weights, such as testes, epididymides, ventral prostate, seminal vesicles, and vas deferens, was observed at different dose levels compared to the control. Changes in sperm dynamics (motility and density) were also observed in the treated groups. Tissue biochemistry results revealed a substantial dose-dependent decrease in various parameters including protein, glycogen, cholesterol, fructose, and sialic acid in different reproductive organs, which might be silver-induced toxicity, whereas recovery groups showed a resurgence of these parameters once the doses were ceased for the following 30 days. In hormone analysis, a decrease in testosterone levels was also observed in a dose-response manner. Testosterone exhibited a correlation with the histopathological examination of the testis, revealing degenerative changes in seminiferous tubules and decreased spermatogenesis. These results support the notion that C. siamea leaf extract AgNPs possess antifertility potential and may be employed as a contraceptive.