Through a solution and casting procedure, a biodegradable poly(butylene adipate) (PBA)-based nanocomposite was prepared by the incorporation of 0.25 wt % of octavinyl-polyhedral oligomeric silsesquioxanes (ovi-POSS) as the nanofiller in the present research. On the basis of the scanning electron microscopy investigation, the ovi-POSS nanofillers not only crystallize but also disperse evenly in the PBA matrix. Compared with PBA, the thermal stability and isothermal crystallization rate of the nanocomposite are obviously improved. The accelerated crystallization process of the nanocomposite should arise from the nucleating effect of ovi-POSS, as the spherulite nucleation density has become greater in the nanocomposite than in PBA; however, the nanocomposite and PBA show the unmodified crystallization mechanisms and crystal structures, despite ovi-POSS.