Amorphous glass-coated microwires display a core-shell-type magnetic structure, whose main components, the inner core and the outer shell, have been extensively studied. In this paper, the interdomain wall that separates these two main components of the core-shell structure is investigated. The wall position and width in microwires with various compositions and dimensions are calculated. Experimental investigation techniques, such as ferromagnetic resonance, ultrahigh frequency giant magnetoimpedance, and axial hysteresis loop measurements, are subsequently employed to investigate those regions of the microwires in which the presence of the interdomain wall is expected to have the most significant effects. The investigation of the interdomain wall unveils aspects of the magnetism of these materials and opens up the way for the development of methods of controlled optimization of their magnetic properties in order to improve their response as sensitive elements in magnetic sensor devices.