In this study, a cross-linking layer which performed as a unidirectional diffusion layer was fabricated onto a polypropylene (PP) mat through UV radiation graft polymerization. On the one hand, the introduction of acrylate monomers enhanced the hydrophobility of the sorbent, and the swelling of PP sorbent provided more spaces, which increased the sorption capacity. On the other hand, the diffusion channels were locked after saturation adsorption. Thus, the retention capacity was dramatically intensified. A reusability test revealed that the cross-linking layer also performed as a scaffold to sustain the inner fibrous structure, which improved the reusability. Also, the oil sorption and retention mechanism were systematically elucidated. The study proposed a potential method to fabricate fibrous sorbent and increase the oil sorption and retention capacity.