Although human adipose‐derived stem cells (hASCs) have great potential as a cell source for stem cell therapy due to their capacity of self‐renewal, long‐term growth, and multipotency with high obtainability through lipoaspiration, little is known about the effects of micro/nano dual‐scale topography on the proliferation and differentiation of the hASCs. In this study, the effects of micro/nano dual‐scale crossed sinusoidal wavy patterns (SIMNs) on the hASC behaviors including cellular alignment, proliferation, and endothelial differentiation are investigated. Various types of microscale, nanoscale, and SIMNs are fabricated on a single polystyrene surface in a step‐gradient manner based on the combined fabrication processes of deep X‐ray lithography, polydimethylsiloxane surface wrinkling, and thermal nanoimprinting process. The cellular alignment, proliferation, and endothelial differentiation of the hASCs are promoted on the SIMNs compared to the microscale or nanoscale sinusoidal wavy patterns. A micro/nano dual‐scale pattern of SIMN160_500, which has a micro‐scale sinusoidal wavy pattern with a wavelength of 160 µm crossed with a nanoscale sinusoidal wavy pattern with a wavelength of 500 nm, is found to be a most effective pattern for synergistically promoting both proliferation and endothelial differentiation of the hASCs with 1.2‐fold and 2‐fold increases, respectively.