Abstract This study replicated a molded plastic substrate with micropatterns by a mold insert employing ultrasonic hot embossing. A plastic substrate and mold insert were combined and heated above the plastic’s glass transition temperature, and then the softened plastic was allowed to flow into the micropattern of the mold insert making use of pressure applied by conventional techniques. A longitudinal ultrasonic wave was added to the ultrasonic hot embossing process. Groove-shaped micropatterns were formed on the surface of the Ni mold insert, and their dimensions were a width of 2 μm and a depth of 200 nm. Polypropylene and poly(methyl methacrylate) were selected as the embossed materials. This study determined the replication and surface properties of the plastic substrate by various process parameters (delay pressure, sonotrode pressure, holding pressure, delay time, ultrasonic duration time, and holding time) of ultrasonic hot embossing.