Phenolic acids have been extensively studied because of their bioactive properties and disease prevention and control capacities. However, undesired odors and taste, low aqueous solubility, and thermal and ultraviolet (UV) light instability severely restrict their application. The aim of this work was to evaluate the enhancement in antioxidative activities of phenolic acids in hollow nanospheres and their stability in terms of their antioxidative activities under harsh conditions. For the first time, we have successfully fabricated hollow short linear glucan (SLG)@gum arabic (GA) nanospheres and hollow in situ SLG/GA hybrid nanospheres by removing the sacrificial starch nanoparticle templates through α-amylase treatment and Ostwald ripening. These two hollow nanospheres had a huge cavity area for the encapsulation of phenolic acids, and their loading capacities were >20%. Furthermore, they can be used as nanoreactors to immobilize phenolic acids, enhance their antioxidative activities, and improve their stability when exposed to high salt concentrations, UV light, or heat treatments.