Three-dimensional (3D) cell culture has revolutionized life sciences, particularly in organoid technologies. Traditional bioscaffold materials, however, complicate the detachment of tumor organoids and hamper the routine use of organoid–immune cell cocultures. Here, we show an acoustic virtual 3D scaffold (AV-Scaf) method to achieve 3D tumor organoid culture, enabling a direct-interacting tumor organoid–immune cell coculture system. The self-organization process of tumor cells is facilitated by a vortex acoustic field, which enables the cell bioassembly and ion channel activation. This approach can significantly enhance the influx of calcium ions, thereby accelerating intercellular interactions of cellular assemblies. We established scaffold-free melanoma and breast cancer organoids using AV-Scaf and cocultured melanoma organoids with T cells. We found that our coculture system resulted in a high activation state of T cells, characterized by notable up-regulation of granzyme B (2.82 to 17.5%) and interferon-γ (1.36 to 16%). AV-Scaf offers an efficient method for tumor organoid–immune cell studies, advancing cancer research and immunotherapy development.