In this study, we design nanostructured antireflection multiwavelength micro-optics that can be used in fiber-optic communication systems. The finite-difference time-domain method was used to search for a moth-eye nanostructure that exhibited a significantly reduced reflectivity in the wavelength range from 1250 to 1650 nm. Further, a multiobjective optimization algorithm was developed for optimizing the wideband reflectance at an oblique incidence from 0° to 30°; this optimization was implemented for a parameter space in which the geometrical arrangement, radius, height, and period of the nanopillars could be included. Subsequently, at a wavelength of 1550 nm, a near-zero reflectance (0.012%) was obtained via simulation, whereas an experimental value of 0.157% was obtained when the samples fabricated based on the optimal design was used. Furthermore, this discrepancy between the simulated and experimental results was analyzed by considering the change in the reflective index with the wavelength.