Titanium dioxide nanoparticles (TiO2 NPs) have attracted attention for their versatile applications across environmental, agricultural and biomedical fields. Known for strong photocatalytic properties, TiO2 NPs effectively degrade organic contaminants and eliminate pathogens, including bacteria and viruses. Recent advances, such as doping and surface modifications, have enhanced their ability to absorb visible light, improving their efficiency for water purification, surface sanitization, and medical treatments. In addition to photocatalytic and antimicrobial functions, TiO2 NPs are increasingly used to prime plant defense mechanisms against abiotic stressors. These nanoparticles boost antioxidant enzyme activity, improve cellular structure, and regulate gene expression, leading to enhanced resilience in plants. TiO2 NPs also show promise in sustainable agriculture by increasing plant vigor and productivity under stressful conditions. They help plants tolerate heavy metal toxicity, oxidative damage, and fungal infections, contributing to higher crop yields. Moreover, their potential to reduce the need for chemical pesticides, coupled with their ability to improve photosynthesis and nutrient uptake, makes TiO2 NPs a valuable tool in modern agricultural practices.