ABSTRACT Interstitial electronic states, commonly found in F‐centers and electrides, have garnered significant attention in materials discovery, and applications spanning catalysis and electronics. Here, we demonstrate that active‐metal‐rich intermetallics serve as a platform for forming diverse cationic cages that accommodate distinct interstitial electrons. This arises from two key factors: (1) the high atomic density of active metals, promoting their aggregation to form cages; and (2) the hig