The preparation of magnetic inks stable over time made of L1(0)-ordered FePt nanoparticles, thiol-ended poly(ethylene glycol) methyl ether (mPEO-SH) compatibilizing macromolecules and asymmetric polystyrene-block-poly(ethylene oxide) copolymers (BCP) as a subsequent self-organizing medium was optimized. It was demonstrated that the use of sacrificial MgO shells as physical barriers during the annealing stage for getting the L1(0)-ordered state makes easier and more efficient the anchoring of compatibilizing PEO macromolecules onto the nanopartides surface. L1(0)-FePt grafted nanopartides have shown a good colloidal stability and affinity with the PEO domains of the BCP leading to L1(0)-FePt/BCP composite thin layers with individual magnetic dots dispersed in the BCP matrix.