Abiotic stresses adversely affect the growth and productivity and elicit a series of morphological, physiological, biochemical, and molecular changes in plants. Drought, temperature extremes, and salinity are the most common abiotic stresses that plants encounter. Molecular chaperones are key components of the cellular proteomic machinery that are employed in a wide range of cellular pathways under both normal and extreme conditions to maintain cellular homeostasis. Molecular chaperones interact with misfolded or native proteins and help in their proper folding. Moreover, various other chaperones such as protein disulfide isomerase (PDI), calnexin/calreticulin, and cyclophilin have been reported in various plant species in response to abiotic stresses. We summarize here the structure and functions of various molecular chaperones, mainly heat shock proteins (HSPs), calnexin/calreticulin, and other chaperones. We also refer to the various reports regarding their putative role in plant species under different abiotic stress conditions. We describe the structure of domains and motifs in HSPs. We also summarize the mechanism of these molecular chaperones and their signal transduction cascades.