In recent years, as a result of anthropogenic activities, a rise in environmental stresses has been observed. Sessile organisms such as plants make use of signalling in order to interpret and respond appropriately to environmental changes. An evolutionary conserved signal transduction module i.e., mitogen-activated protein kinase (MAPK) is a component of kinase module engaged in different cellular signalling responses in eukaryotes including plants. They receive the extracellular signal and transmitted it to the nucleus for maintenance of cellular homeostasis. The cascade of MAPK is based on 3 components i.e., MAPK kinase kinase (MAPKKK), MAPK kinase (MAPKK), and MAPK; they are connected with each other by phosphorylation mechanism and finally transmit the signals to a particular transcription factor/s (TxFs). In plants, MAPK-based signalling can be regulated by different phytohormones. Not only cell division and differentiation, MAPK signalling plays a crucial role in various biotic and abiotic stress by generating antioxidative mechanism within the cell. Rampant industrialization and subsequent use of various agrochemicals make soil polluted by piling the soil with different kinds of heavy metals which is not essential to human beings as well as for the plants to survive. The present review is based on the signalling mechanism of MAPK cascade of plants in response to heavy metal stress (HMs).