Objective: This study aimed to discover safe antibacterial and antibiofilm agents from natural sources to control resistant bacteria. Methods: C. gileadensis leaves and stems were collected, identified, and extracted using different organic solvents, methanol, ethyl acetate, chloroform, and hot water. The tested bacteria were multidrug-resistant Escherichia coli, Acinetobacter baumannii, Listeria monocytogenes, Serratia marcescens, Klebsiella pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa. Crystal violet method was used to detect biofilm formation while the phenol-sulphonic acid method to measure exopolysaccharide contents, which are an effective factor in biofilm formation. Results: No significant differences were noted in the biological activities between leave and stem. Ethyl acetate and chloroform extracts showed lower activities. Still, hot water extract showed the weakest activities.There is a synergistic effect between the Commiphora extract and some antibiotics, especially Amoxicillin, Polymixin B, and Tetracycline. The highest inhibition of biofilm was recorded against K. pneumonia which had the highest EPS content (0.29 ±0.04 μg/mg of cells), decreased after treatment with plant extract by 39%. Cytotoxicity studies using Artimia salina as a test organism were conducted for the methanolic extracts, which showed antitumor activity against two cell lines, MCF-7 (breast cancer) and HepG2 (hepatocellular carcinoma). Commiphora extract showed antioxidant activity using two different protocols. Conclusion, the methanolic extract of Commiphora singly or in combination with antibiotics inhibit many pathogenic bacteria that form biofilm and recorded antitumor and antioxidant activities.