Amphiphilic oat β-glucan derivatives carrying octenylsuccinic groups as hydrophobic moieties have been synthesized. Materials with a different degree of substitution (DS) and weight-average molecular weight (Mw) for oat β-glucan were prepared and characterized using elemental analysis, infrared (IR) spectroscopy, and high performance size exclusion chromatography (HPSEC). Dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopy (TEM) revealed that octenylsuccinate oat β-glucan (OSG) can self-assemble into spherical micelles in water with an average size ranging from 175 to 600 nm. OSG micelles were negatively charged as indicated by ζ-potential measurement. The critical micelle concentration (CMC) of OSGs varied from 0.206 to 0.039 mg/mL, depending on the DS and Mw of the oat β-glucan. It was found that the presence of OSG micelles in aqueous solution could significantly enhance the solubility of curcumin by 880 fold. Thus, OSG might have great potential in applications as hydrophobic nutrient delivery carriers.