An experiment was carried out in Sakha Research Station, Kafrelsheikh governorate, Egypt during the 2018-2019 seasons to isolate the cyanobacteria dominated in the soil samples of rice fields polluted by two pesticides (carbofuran and penoxsulam). These cyanobacterial isolates were identified and the best isolates, regarding growth activities and nitrogen (N₂) fixation capacities, were chosen and further applied to the rice field to study their effect on rice yield under different urea concentrations (0, 35 and 69 kg N₂/fed). Data revealed that nine cyanobacterial isolates were successfully obtained and purified. A growth curve experiment was conducted on these isolates and revealed that three isolates (Nostoc muscorum, Anabaena cylindrica, and Anabaena variabilis) had the best growth activities and capacities for N₂ fixation. Within limit, both pesticides showed stimulation of both cell growth and N₂ fixation. With higher concentrations, these values tended to decline due to the possible inhibitory or toxic effect of these pesticides. Generally, cyanobacterial isolates were less tolerant to penoxsulam and were inhibited at lower concentrations compared to carbofuran. With carbofuran application on rice field (Egyptian hybrid rice 1 variety), the interaction between cyanobacteria and urea resulted in the highest grain yield with the recommended dose of urea (69 kg N₂/fed), while the highest 1000-grain weight was obtained with half the recommended dose of urea (35 kg N₂/fed). Moreover, the use of a mixture of cyanobacterial species rather than a single one resulted in more satisfactory results.