To meet the increased demands for food from the growing global population, modern technologies and advanced agronomical methods, such as the use of effective herbicides and pesticides to boost agricultural production, have been developed. Similarly, with the rise in need for colorants for textiles, paints, and coatings, excessive amounts of toxic synthetic dyes are being used in industries. The detrimental effects of such approaches on the ecosystem have raised serious concerns worldwide. The persistent use of toxic chemicals globally for decades has led to contaminated groundwater and soil, which ultimately causes diseases in human beings and animals. Nanotechnology is now emerging as a promising tool not only to sustain industries and reduce waste, but also to offer effective and efficient solutions to environmental remediation problems. This chapter focuses on the photocatalytic degradation of pollutants produced from dyes, and from the agricultural and pharmaceutical industries, using ZnO-based nanomaterials as photocatalysts.