Background: Kaempferia parviflora Wall. Ex. Baker (Black ginger) is an important medicinal plant used as a health-promoting tonic i.e., both a stimulant and a vitalizing agent in Thailand. Research findings are available on its aphrodisiac and anti-inflammatory activities. So far, there is no research work conducted on immunomodulatory effect of K. parviflora. Objectives: The present study was carried out to evaluate the immunomodulatory effect of ethanolic extract of rhizomes of K. parviflora in cyclophosphamide-induced immunosuppression in Swiss albino mice. Materials and Methods: Immunomodulatory status was assessed by physiological, hematological, biochemical, and histopathological observations. The weight of organs such as liver and spleen was recorded at the time of sacrifice. Gas chromatography mass spectrophotometry (GC-MS) analysis was performed for profiling compounds present in the extract. Results: Significant increase in body weight was observed on 12th day in K. parviflora-treated immunosuppressed mice. In hematological parameters, there was significantly higher lymphocyte count for K. parviflora-treated immunosuppressed mice. In hemagglutination test, conducted for the evaluation of humoral immune response, both K. parviflora alone and K. parviflora-treated immunosuppressed mice showed significant increase in titer value compared with cyclophosphamide control. Bone marrow cellularity test performed for evaluation of cellular immune response showed cyclophosphamide control group with significant lower bone marrow cellularity on 12th and 19th day while K. parviflora alone-treated and K. parviflora-treated immunosuppressed mice showed a significant increase in the bone marrow cellularity. The result of histopathology of spleen revealed to prevent the depletion of red pulp and white pulp on 12th day, and this prevention was marked on 19th day. GC-MS profiling showed that the extract contained eight compounds. Majority of the compounds belong to flavonoids class which might have helped in immunomodulation. Conclusion: The results of the present study revealed that the test extract possessed promising immunomodulatory activity.