The leaf of citrus family is well known for its odorous characteristics, which are stimulated by the content of essential oil within the leaves. However, not all-citrus leaves have been utilized optimally to meet its highest value. As potential herb, the leaf of sweet orange (Citrus sinensis) is suspected to have antimicrobial activity that may increase the shelf life of food, which was the aimed of this study. Three solvent extractions were conducted toward the leaves using hexane, ethyl acetate, and ethanol as solvents. The acquired extracts were then evaluated for the antimicrobial activity using well diffusion method, phytochemical test, and toxicity test to determine the best solvent for the extraction process, which was then utilized further to obtain the rest of the extract for the application on fish and challenge test. It was found that the best solvent for extracting leaves was ethanol, with maximum inhibition toward Gram negative bacteria (i.e. Eschericia coli and Enterobacter aerogenes, yielding 0.749 cm for 20% ethanol and 0.7425±0.2636 cm in average respectively). The application on fish showed that the extract could not inhibit the growth of microorganisms in fish well; but the application of 5 MIC extract started to exhibit little inhibition trend. The application of freezing method as a storage method was proven to inhibit the growth of natural microorganisms in fish well compared to the refrigeration method. Based on the physical properties evaluation of the fish, fishes were spoiled (scored below 7 based on SNI 01-2729.1-2006) starting from the third day of refrigeration storage, and the fourth day in freezing storage. The application of Citrus sinensis was proven to prolong the shelf life of the fish up to the fourth day in refrigeration storage, and to the sixth for freezing storage.