Plant pests and diseases are among the major factors responsible for reducing the yield and quality of agricultural crops worldwide. Insects, mites, nematodes, fungi, bacteria, and plant viruses can cause substantial economic losses by disrupting essential physiological processes, including photosynthesis, water and nutrient uptake, and the growth and development of various plant organs. According to the International Plant Protection Convention (IPPC), plant pests affect approximately 20–40% of global crop production annually, with the economic losses caused by plant pests and diseases estimated to exceed USD 220 billion per year. Although the continuous and indiscriminate use of chemical pesticides can reduce pest and pathogen populations in the short term, it may result in undesirable consequences, including the development of resistance, environmental contamination, reductions in natural enemy populations, and increased risks associated with pesticide residues in agricultural products. Integrated pest and disease management is an ecosystem-based approach that combines cultural, mechanical, physical, biological, genetic, and chemical methods to maintain pest and pathogen populations below economically damaging levels. This article reviews the major plant pests and pathogens, the principles of integrated management, and the role of biological and emerging approaches in achieving sustainable agriculture.