Electrospun composite nanofiber mats consisting of polyurethane (PU) and nontoxic tungsten powder are manufactured via electrospinning for use as X‐ray shielding materials. Upon systematical formation of tungsten‐PU composite nanofiber layers, heat and pressure are simultaneously treated to design light‐weight mats containing various amount of tungsten metals. After examining their structural and physical properties, the X‐ray mass attenuation coefficient, nitrogen permeability, and flexibility of the resulting mats are compared to conventional film‐type shielding mats. While the nanofiber‐based composite mats still exhibit a comparable X‐ray mass attenuation coefficient (9.64 cm2/g), their gas permeability (8.56 L/min) and flexibility (bending angle of 28.8°) are almost two and five times higher than those of conventional mats, respectively. This work clearly demonstrates the preparation of effective composite mats with controlled properties for the development of nontoxic shielding suits that can replace conventional lead‐based materials possessing environmental and health concerns.