The experiment was conducted in Al-Diwaniyah Governorate, Iraq, during the 2022-2023 agricultural season (three months) on lettuce (Lactuca sativa var. capitata). The study aimed to investigate the effect of spraying lettuce plants with an algal extract from Cladophora glomerata, isolated from a stream at the University of Al-Qadisiyah, at concentrations of 2 and 4g/ L. Results indicated an increase in vegetative growth characteristics, including plant height, number of leaves, fresh weight, and total leaf area, with the highest averages being 20.66cm, 24 leaves, 135g, and 5260.26cm², respectively. Additionally, chemical content characteristics such as carbohydrates, vitamin C, total nitrogen, phosphorus, sulfur, and iron showed mean values of 1.6%, 4.12mg/ 100g fresh weight, 3.72%, 0.25%, 72.45mg/ g dry weight, and 1.32%, respectively, when treated with 4g/ L of algal extract. In comparison, control plants showed the lowest values. Treatment with 2g/ L of algal extract resulted in higher mean values for dry weight, total chlorophyll, carotenoids, protein, vitamins A and K, potassium, zinc, calcium, and fiber, with values of 11.64g, 1.89mg/ g, 0.21%, 1.39%, 200.72mg/ 100g fresh weight, 108.47mg/ 100g fresh weight, 1.2%, 2.94mg/ 100g fresh weight, 60.9mg/ 100g, and 1.6%, respectively, compared to the control plants. Statistical analysis revealed significant differences (P≤ 0.05) between all parameters, except for plant height and iron, where the differences were not significant among the experimental treatments.