The adverse effects of antibiotics and the evolving resistance strategies of bacteria have made their use extremely challenging in recent times. Therefore, ongoing research is required to find novel antimicrobial chemicals so that safer and more effective medications can be created. This study evaluates the antibacterial activities of crude extracts from Corallina officinalis as alternative antibiotics. Corallina officinalis seaweed was collected from Alexandria, Egypt (31◦21′46″N, 29◦88′49.4″E) during March 2022. Different solvents (ethanol, methanol and acetone) were used to extract the antibacterial substances from this seaweed and were examined against three pathogenic bacteria, Staphylococcus aureus, Citrobacter sp. and Klebsiella pneumoniae by agar well diffusion method. The maximum activity was associated with the appearance of a clear zone (30.2 ±0.08mm) which was recorded when using 200mg/ml of acetone-extract against Klebsiella pneumonia and minimum activity (15.9 ±0.08mm) was recorded when using 200mg/ml of ethanol-extract against Citrobacter sp. Scanning electron microscope showed the cells were damaged when treated with seaweed extracts. The GC-MS chromatographic analysis of the Corallina officinalis revealed the presence of various bioactive compounds such as 1-iodotridecane (5.142%), cholesterol (19.365%), nonadecane (4.806%) %), pentadecane (6.237%), docosane (1.639%), tetramethyl-5'-thymidylic acid (7.042%). The results of FTIR analysis confirmed the presence of phenol, alcohols, alkanes, carboxylic group, ketone group, aromatics and aliphatic amines. Our results suggest the potential of Corallina officinalis extracts as natural and effective promissing source of new antibiotics.