Natural elicitors play a vital role in activating plant defense mechanisms, aiding plants in resisting infections from various pathogens. These elicitors, such as oligosaccharides, proteins, and lipids, initiate immune responses by simulating the presence of a threat. This prompts plants to strengthen their cell walls, generate antimicrobial compounds, and activate signaling pathways. Plant pathogens, including bacteria, fungi, and viruses, continually seek to overcome these defenses. For example, bacterial pathogens such as Pseudomonas syringae, Ralstonia spp., and Xanthomonas spp. significantly impact crop production by releasing virulence factors into plant tissues, leading to widespread yield losses. Similarly, fungal pathogens and viruses also threaten crop health by manipulating plant defenses. Insect herbivores, through close associations with their host plants, utilize herbivore-associated elicitors (HAEs) present in oral secretions, frass, and egg fluids to suppress plant defenses. These HAEs are recognized by pattern-recognition receptors (PRRs) in plants, initiating specific defense responses. Traditional control methods, including chemical pesticides, copper-based bactericides, and antibiotics, are often ineffective and harmful to human health and the environment. As a result, research has focused on environmentally sustainable alternatives such as abiotic and biotic elicitors. Abiotic elicitors, chemicals of non-biological origin, and biotic elicitors, such as HAEs, activate plant defense mechanisms through early signaling events involving calcium ions (Ca2+), reactive oxygen species (ROS), and mitogen-activated protein kinase pathways. These signaling cascades induce both local and systemic resistance, reprogramming plant metabolism and transcription to defend against various pathogens and herbivores. This chapter explores the use of natural compounds as elicitors to enhance plant resistance against a wide range of diseases caused by bacterial, fungal, and viral pathogens and insect herbivores. The main aim is to promote sustainable crop protection, enhance plant immunity, and provide long-term solutions to disease and pest management, ultimately contributing to global food security.