<p>Nanoparticles (NPs) have become pivotal in enhancing agricultural productivity and plant resilience due to their unique properties and ability to interact at the molecular level. This review explores the intricate crosstalk between NPs and key signaling molecules, reactive oxygen species (ROS), nitric oxide (NO), hydrogen sulfide (H₂S), calcium ions (Ca²⁺), and phytohormones under abiotic and biotic stress conditions. ROS are critical in stress responses, acting as damaging agents and signaling entities; NPs can modulate ROS levels, either mitigate oxidative stress or induce it depending on their nature and concentration. Similarly, NO, a versatile signaling molecule, is influenced by NPs like silver and gold, which can enhance antioxidant defenses and activate stress-responsive genes. H₂S, another gasotransmitter, interacts with carbon-based NPs, improving stress tolerance by modulating antioxidant enzyme activities and related gene expressions. Ca²⁺ ions, essential for various stress responses, can have their signaling pathways altered by NPs such as cerium oxide, impacting stomatal behavior and root development. Phytohormones like auxins, cytokinins, and so on, are also modulated by NPs, affecting plant growth and stress resilience. This comprehensive review underscores the complexity of nanoparticle (NP) interactions with plant signaling pathways and highlights the potential of NPs to enhance plant stress tolerance. Further research is essential to unravel the precise mechanisms of these interactions, paving the way for optimized NP formulations tailored to specific stress conditions to maximize their beneficial impacts on plant health and productivity.</p>