Emerging molecular diagnosis requires ultrafast polymerase chain reaction (PCR) on chip for rapid precise detection of infectious diseases in the point-of-care test. Here, we report nanoplasmonic on-chip PCR for rapid precision molecular diagnostics. The nanoplasmonic pillar arrays (NPA) comprise gold nanoislands on the top and sidewall of large-scale glass nanopillar arrays. The nanoplasmonic pillars enhance light absorption of a white light-emitting diode (LED) over the whole visible range due to strong electromagnetic hotspots between the nanoislands. As a result, they effectively induce photothermal heating for ultrafast PCR thermal cycling. The temperature profile of NPA exhibits 30 cycles between 98 and 60 degrees C for a total of 3 min and 30 s during the cyclic excitation of white LED light. The experimental results also demonstrate the rapid DNA amplification of both 0.1 ng mu L-1 of lambda-DNA in 20 thermal cycles and 0.1 ng mu L-1 of complementary DNA of Middle East respiratory syndrome coronavirus in 30 thermal cycles using a conventional PCR volume of 15 mu L. This nanoplasmonic PCR technique provides a new opportunity for rapid precision molecular diagnostics.