Salinity stress affects over 1.1 billion hectares of arable land globally, posing a significant challenge to crop productivity. It disrupts plant photosynthesis through osmotic and ionic imbalances, ion toxicity, and oxidative stress. Salinity impairs both stomatal (CO2 intake) and non-stomatal (electron transport, enzyme activity) processes, inhibits PS-II function, elevates reactive oxygen species (ROS), and suppresses Calvin cycle enzymes such as Rubisco and Sedoheptulose-bisphosphatase (SBPase). Photosynthesis under salinity is marked by reduced chlorophyll content, gas exchange, photochemical efficiency, and enzyme activity. For instance, under 100–150 mM NaCl, chlorophyll a and b content declined by 35–40% in rice and wheat, respectively. Photosynthetic rate dropped by 33–40% in maize, barley, and cotton, Soybean and sunflower experienced a 50% reduction in stomatal conductance and transpiration, the Fv/Fm ratio, indicating PS-II efficiency, decreased by 10–15% in tomato and rice and Rubisco activity declined by over 40% in wheat and barley under salinity stress. To counteract these effects, several strategies have proven effective in restoring photosynthetic function. Treatments with glycine betaine, silicon, phytohormones, biochar, beneficial microbes, aquaporin gene expression, and targeted lighting help in recovering chlorophyll content, gas exchange, electron transport, and Rubisco activity while reducing ROS accumulation. These interventions enhance plant growth and yield under saline conditions. Improving photosynthesis in salt-affected crops supports Sustainable Development Goals, reducing poverty and improving food security and enhancing nutrition. An integrated approach combining physiology, agronomy, biotechnology, and molecular tools offers a sustainable path for agriculture in salt-stressed environments.