Nanoparticles (NPs) exhibit distinctive characteristics that increase their biochemical reactivity. As plants, being immobile, are consistently exposed to NPs in the environment, these particles act as abiotic stressors at sub-toxic levels and become phytotoxic at higher concentrations. In general, NPs induce their toxic effects by producing reactive oxygen species (ROS), prompting plants to activate enzymatic and nonenzymatic antioxidant defense mechanisms in response. A crucial outcome of this defense mechanism is the heightened or de novo synthesis of secondary metabolites, such as phenolics (including flavonoids), terpenes, steroids, nitrogenous compounds, and sulfur-containing compounds, many of which hold significant economic value. This chapter provides an overview of the existing knowledge regarding the use of various NPs as inducers of economically valuable secondary metabolites in different plants, both in vivo and in plant cell and tissue cultures. It also explores their impact on related enzymes and genes. The text touches upon the technology employed for harvesting secondary metabolites using NPs and offers a brief explanation of the likely mechanism through which NPs influence plant secondary metabolism. Lastly, a critical evaluation is presented on the factors influencing the optimal utilization of this technology, along with future directions that could be explored to facilitate its commercial exploitation.