With the development of optical anti‐counterfeiting and the increasing demand for high‐level information encryption, multimodal luminescence (MML) materials attract much attention. However, the discovery of these multifunctional materials is very accidental, and the versatile host suitable for developing such materials remains unclear. Here, a grossite‐type fast ionic conductor CaGa ₄O ₇, characterized by layered and tunnel structure with excellent defect tolerance, is found to meet the needs of various luminescent processes. Almost all luminescent modes, including down/up‐conversion luminescence (DCL/UCL), long persistent luminescence (LPL), mechanoluminescence (ML), and X‐ray excited optical luminescence (XEOL), are realized in this single host. Full‐spectrum (from violet to near‐infrared) photoluminescence and ML as well as multicolor XEOL are achieved by simply changing the doped luminescent …