Polymer brushes have been used as supports for the immobilization of Keggin-type polyoxometalates (POMs) catalysts on poly(vinylidene fluoride) (PVDF) membranes by electrostatic-assembly. The poly(4-vinylpyridine) (P4VP) polymers are effectively grafted from PVDF membranes via surface-initiated atom transfer radical polymerization with activators generated by electron transfer (SI-AGET ATRP), and the P4VP-grafted PVDF membranes are characterized via ATR-FTIR, XPS, SEM, and AFM. Subsequently, the quaternization of the P4VP brushes process creates a membrane with a positive charge. The pendant pyridine and pyridinium groups facilitate the electrostatic assembly of POMs onto the P4VP-grafted membrane, thereby fabricating a well-designed membrane with potential catalytic applications. Therefore, such systems are interesting candidates for the heterogenization of POMs onto polymer-grafted membranes.