Nanoscale channels are of great interest for various applications and a functional nanochannel-based device also requires microscale components such as microchannels and microwells for sample loading. We report a novel non-cleanroom process to generate centimeter-sized and highly-ordered arrays of nanochannels/microwells by DNA combing and imprinting (DCI). In this method, DNA nanowires are formed first by molecular combing performed on an array of micropillars and are coated with metals by sputtering coating to produce metallic nanowires with controllable diameter. The metallic nanowires are then converted to polymeric nanochannels by imprinting using the nanowires as sacrificial templates. At the same time, the micropillars are converted to polymeric microwells by imprinting. Compared to other micro/nanofabrication methods, DCI is simple, inexpensive, and capable of generating large and well-defined nanochannel/microwell arrays with potential applications such as biomedical sensing and separation.