In this work, we have synthesized oleylamine (OM)-coated hydrophobic monodispersed SPIONs with an average particle size of ~9 nm via thermal decomposition method. The as-prepared hydrophobic SPIONs are co-encapsulated along with a drug (curcumin, Cur) within the mixed micelles based nanoformulations which is made of d-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) and Pluronic F127 while keeping the TPGS:F127 ratios at 100:0, 75:25, 50:50, 25:75 and 0:100. Then, the nanoformulations are characterized for hydrodynamic size via dynamic light scattering (DLS) technique, and drug/SPIONs encapsulation efficiencies are determined via UV-vis spectroscopy. Among all the nanoformulation, the mixed micelle with 50:50 TPGS:F127 has exhibited relatively lower hydrodynamic diameter (Dh) (~ 84 nm), better encapsulation efficiencies of Cur and SPIONs (~95% / 56%), and high yield (above 90%). Moreover, morphology and encapsulation of SPIONs/Cur inside the optimized 50:50 TPGS:F127 nanoformulation is confirmed by TEM. In addition, only 10% of Cur is released during 12h time period from optimized nanoformulation indicating the sustained-release property, whereas ~68% of Cur is quickly released in free Cur experiments for the same time period. Hence, the SPIONs/Cur are efficiently co-encapsulated inside the TPGS:F127 mixed micelle based nanoformulation which could be used for further biomedical applications.