Polymer nanocomposites containing layered oxides have been widely researched because of the improved properties compared to the polymer alone. Recently, our group has explored the incorporation of layered perovskites into various polymer matrices to prepare novel nanocomposite materials. To promote exfoliation and improve the polymer-perovskite interactions, covalently modified perovskites were investigated. Interlayer surface modification of protonated Dion-Jacobson perovskites, HCa2Nb3O10 and HLaNb2O7, has been achieved using various organic functionalities. The synthesis, surface modification, and characterization of the covalently modified perovskites, along with the preparation of novel polymer-perovskite nanocomposites, will be discussed