The potential of bacteria‐based immunotherapy lies in its ability to inherently enhance immune responses. However, the “liveness” of bacteria poses risks of bacterial escape, nonspecific immuno‐stimulation, and ethical concerns, limiting their acceptability in immunotherapy. In this scenario, nonliving empty bacterial‐cell envelopes, named bacterial ghosts (BGs), have emerged as immuno‐stimulants with the potential to side‐step the limitations of live bacterial therapies. This study demonstrates the capability of BGs in modulating the functionality of NK‐92 cells and Caenorhabditis elegans (C. elegans), as well as perform as cytokine‐therapy adjuvants. BGs were obtained through a pH‐driven culture method, and were validated for their structural and chemical integrity via electron microscopy and spectroscopy. In NK‐92 cells, BGs have shown significant immuno‐stimulation by boosting the gene‐expression of perforin, granzyme‐B, Fas‐L, and interferon‐gamma by factors of 3.5‐, 1.5‐, 12.5‐, and 8.6‐folds, respectively. Combined BG and IL‐12 treatment yielded a notable 10.2‐fold increase in interferon‐gamma protein expression in 24 h. The BGs also significantly influenced the innate immune response in C. elegans through the upregulation of lysozyme genes viz., ilys‐3 (8.8‐fold) and lys‐2 (3.1‐fold). Our investigation into the impact of BGs on natural killer cells and C. elegans highlights its potential as a valid alternative approach for new‐age immunotherapy and cytokine augmentation.