Nanofibers prepared by electrospinning technique are extensively applied as building blocks for tissue-engineered scaffolds because of their high resemblance to natural extracellular matrix (ECM) and the capacity to provide more cell contacts than microfibers. However, conventional electrospun scaffolds only allow superficial growth of cells in that the size of inter-fiber pores is much smaller than the size of cells. By taking advantage of the positive correlation between fiber diameter and pore size in fibrous materials, we report here a simple method for fabricating poly-L-lactic acid (PLLA) microfiber scaffold with longitudinally aligned nanogrooves on fiber surface. Three-dimensional (3D) and structurally stable PLLA scaffolds with an average pore size of 16 μm were successfully acquired when the fiber diameter was 4.22 μm. The topographical cues from nanogrooves ensured fast cell adhesion of scaffolds, whilst the large inter-fiber pores enabled sufficient cell infiltration. Moreover, the nanogrooved microfiber scaffold showed improved curative effects of wound healing in a rat skin injury model, making us believe its practical significance in biomedical areas that requires fast cell adhesion and high cell infiltration.