Volatile organic compounds (VOCs), such as isoprene, monoterpenes, and sesquiterpenes, encompass a wide range of chemicals emitted by plants, significantly influencing plant physiology and ecosystem dynamics. Among these VOCs, isoprene stands out as a particularly fascinating subject of research. This chapter delves into the dual role of isoprene as both a natural antioxidant and a plant regulator. Isoprene’s ability to stabilize plant membranes and mitigate oxidative stress caused by ground-level ozone and elevated temperatures has sparked interest in its potential antioxidant functions. While the antioxidant activities of isoprene are increasingly recognized, the byproducts resulting from its interaction with reactive oxygen species remain under investigation. Notably, isoprene emission is restricted to certain plant species, indicating its selective role in modulating plant responses to various biotic and abiotic stresses. The interaction of isoprene with reactive oxygen and nitrogen species within leaves further suggests its involvement in complex plant signalling pathways and adaptive mechanisms. The intricate relationship between isoprene, its antioxidant properties, and its regulatory functions underscores the dynamic interplay between plants and their environment. Further research is essential to fully elucidate isoprene’s role as a natural antioxidant, plant regulator, or both. This chapter emphasizes isoprene’s potential as a dual-functioning compound that not only shields plants from environmental stresses but also influences their ecological responses and adaptations.