Immune responses must be strictly regulated to prevent autoimmune and infectious diseases and to protect against infectious agents. As people age, their immunity wanes, leading to a decrease in lymphocyte production in bone marrow and thymus and a decline in the efficacy of mature lymphocytes in secondary lymphoid organs. This study explores the immune-boosting potential of (YGD) in enhancing the immune system by activating immune cells. In our experiments, cyclophosphamide (Cy) treatment led to a significant decrease in primary splenocyte viability. However, subsequent treatment with YGD significantly improved cell viability, with doses ranging between 1 and 25 μg/mL in Cy-treated splenocytes. Flow cytometry analysis demonstrated that the Cy group exhibited reduced positivity of CD3 T cells and CD45 leukocytes compared to the blank group. In contrast, treatment with YGD led to a notable, dose-responsive increase in these immune cell types. In our experiments, YGD was orally administered to Cy-induced immunosuppressed mice at 20 and 100 mg/kg doses for 10 days. The results indicated a dose-dependent elevation in immunoglobulin (Ig)G and IgM levels in the serum, emphasizing the immunostimulatory effect of YGD. Furthermore, the Cy-treated group showed decreased T cells, B (CD19) cells, and leukocytes in the total splenocyte population. Yet, YGD treatment resulted in a dose-dependent reversal of this pattern, suggesting its ability to counter immunosuppression. Notably, YGD was found to effectively stimulate T (CD4 and CD8) lymphocyte subsets and natural killer cells, along with enhancing Th1/Th2 cytokines in immunosuppressed conditions. These outcomes correlated with the modulation of BCL-2 and BAX expression, which are critical for apoptosis. In conclusion, YGD has the potential to bolster immune functionality through the activation of immune cells, thereby enhancing the immune system's capacity to combat diseases and improve overall health and wellness.