A field experiment was conducted once at Isabela State University, Jones, Isabela, Philippines during the wet season of 2018 to determine the impact of seaweed extract added with varying levels of inorganic fertilizer on the growth and yield of upland rice (Oryza sativa L.) cultivars. In the study, five fertilizer levels and a farmer’s practice as a control combined with seaweed extract was used. The study used Randomized Blocks in a Factorial Scheme with six treatments replicated thrice as follows: Factor A: V1-Pinilisa, V2-Palawan and Factor B: F1-150-100 kg NP ha-1 (Farmer’s Practice), F2-40-10 kg NP ha-1 (100% Recommended Rate), F3-20-5 kg NP ha-1 (50% Recommended Rate), F4-40-10 kg NP ha-1 + 3 L/ha. Seaweed extract, F5-20-5 kg NP ha-1 + 3 L/ha. Seaweed extract and F6-3L/ha. Seaweed Extract. The findings revealed that seaweed extract combined with inorganic fertilizer application influenced the growth and yield of rice. Pinilisa cultivar obtained a higher yield compared to the Palawan cultivar. The combination of seaweed extract and inorganic fertilizer shows highly significant differences especially concerning the number of productive tillers, filled grains, 1000 grain weight and straw weight. The return on investment showed that Pinilisa cultivar fertilized with 3 L seaweed extract is more economical in upland rice obtaining the highest with 95.47%. Seaweed extract as foliar fertilizer can be applied not only in rice but also in other crops. Application of seaweed extract on rice can reduce the amount of fertilizers.