An integrated circuit (IC) package substrate including a glass core having a cavity filter structure, and related devices and methods, are disclosed herein. In some embodiments, an IC package substrate may include a core made of glass, and the core including a first core portion having a first surface and a trench and a ridge in the first surface, the trench and the ridge lined with a conductive material; and a second core portion having a second surface, the second surface lined with the conductive material, wherein the first surface of the first core portion is physically coupled to the second surface of the second core portion forming a cavity filter structure.