Water scarcity has become a major challenge for agriculture, particularly in arid and semi-arid regions where irrigation is essential for sustaining crop and forage production. As freshwater supplies face growing pressure from climate change, urban growth, and industrial use, there is increasing interest in exploring alternative water sources to support sustainable agriculture. Produced water, a byproduct of oil and gas extraction, may represent an alternative water source in water-limited regions like the southwestern United States and the Middle East. However, raw produced water often contains high levels of salinity, trace metals, hydrocarbons, and naturally occurring radioactive materials, which cause risks to soils, crops, livestock, and food systems. This review synthesizes peer-reviewed studies up to January 2026 and reports on the agricultural application of treated produced water, focusing on its effects on soil properties, crop growth, yield, and forage nutritive quality. Existing research shows that treated produced water could be used for grain as well as forage crops under controlled conditions, but poorly treated and managed applications can lead to increases in soil salinity, structural degradation, reduced nutrient uptake, and hindered crop performance. In forage systems, irrigation with treated produced water has also been associated with changes in nutritive value, increasing concerns for livestock health. Several knowledge gaps remain, including limited long-term field studies, insufficient information on crop-specific contaminant thresholds, incomplete assessment of treatment and remediation strategies under different environmental conditions, and the absence of a consistent framework for classifying the chemistry of treated produced water for agricultural applications. Addressing these gaps through integrated soil, crop, and water research and the development of clear policies and guidelines is essential for determining whether treated produced water can be safely and sustainably used in agriculture under growing water scarcity.