The paramount challenge in design and synthesis of materials for vapor-phase elemental mercury (Hg0) immobilization is to achieve a balance between performance and economy for practical applications. Herein, a newly designed electroless plating coupled with an in situ selenization method was developed to construct a copper selenide (Cu2Se)-functionalized commercial polyurethane sponge (PUS) as an efficient Hg0 trap. Intrinsic features such as easy availability of the raw material, facile preparation, and excellent performance guarantee the Cu2Se/PUS to be applicable in industrial uses. The Cu2Se/PUS exhibits a maximum adsorption capacity (Qm,Cu2Se/PUS) of 25.90 mg·g-1, while this value is 758.80 mg·g-1 when normalized to the Cu2Se coating amount. This value of Qm,Cu2Se is equal to 79.7% of its corresponding theoretical value (Qt,Cu2Se), far exceeding the availability of Cu2Se anchored on other supports. Meanwhile, the Cu2Se/PUS exhibited a quick response for Hg0, with an extremely high uptake rate of 1275.84 μg·g-1·min-1. Even under harsh conditions, the Cu2Se/PUS still immobilizes Hg0 effectively, which is crucial for real-world applications. This work not only provides a promising trap for permanent Hg0 sequestration from industrial sources but also illustrates a versatile platform for the economic fabrication and practical application of advanced functional sponges in diverse environmental remediation.