Antibody-dependent cellular cytotoxicity (ADCC) is crucial for cancer immunotherapy, primarily mediated by the CD16A receptor on human NK cells. Humanized CD16A mice were developed on the CB-17-SCID background for evaluating ADCC-inducing antibody candidates. These mice express human CD16A on NK cells and monocytes/macrophages, successfully eliminating murine FcgR4 expression. Tumor growth studies demonstrated the successful establishment of various human tumor cell lines, and a proof-of-concept study with an anti-CLDN18.2 antibody showed modest anti-tumor efficacy. Overall, these humanized mice provide a suitable model for evaluating ADCC-inducing antibody candidates.