An optical sensor including a planar nano-photonic microlens array and an electronic apparatus including the same are provided. The optical sensor may include: a sensor substrate including a plurality of photosensitive cells for sensing light; a filter layer provided on the sensor substrate; and a planar nano-photonic microlens array provided on the filter layer, and including a plurality of planar nano-photonic microlenses, wherein the plurality of planar nano-photonic microlenses are two-dimensionally arranged in a first direction and a second direction that is perpendicular to the first direction, and each of the planar nano-photonic microlenses include nano-structures arranged such that the light transmitting through each of the planar nano-photonic microlenses has a phase profile in which a phase change curve is convex in the first direction and the second direction.