We present a strategy for intensified biodiesel production in a novel metallic microdevice. Additive manufacturing using selective laser melting was employed to build the metallic device consisting of multiple micro reactors monolithically integrated with multiple micro heat exchangers. This device allows high conversion rate of biodiesel production with concomitant use of rejected heat from an external source to enhance the reaction temperature and, thereby, its output. The biodiesel production was carried out using soybean oil, ethanol, and NaOH as the catalyst. The influence of the reaction temperature and the residence time in biodiesel production was examined. Biodiesel yield increased with the reaction temperature, and a rate of conversion of 99.6% was achieved with a reactor residence time of less than 35 s. The work opens up a pathway to exploit waste heat to intensify biodiesel production and contribute significantly to global sustainability.