Nowadays, infectious and oxidative stress-related diseases are leading to many deaths worldwide. Tetraena simplex, a new species (synonym) that is mainly grown in Oman, has traditionally been used as a medicine for asthma. This study aimed to assess antioxidant and antibacterial activities of T. simplex extracts of various polarities using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and agar gel diffusion assays. Among the six extracts prepared, ethyl acetate extract showed the highest antioxidant activity and hexane extract showed the lowest antioxidant activity. Antioxidant activity of the extracts decreased in the order of ethyl acetate > dichloromethane > water > butanol > methanol > hexane. Similarly, antibacterial activities, indicated as inhibition zones, of the six extracts at four concentrations were assessed against two gram-positive bacteria (Streptococcus pneumoniae and Staphylococcus aureus) and three gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, and Proteus bacilli). No extract showed antibacterial activity against the tested bacteria at any concentration. Therefore, the ethyl acetate extract of T. simplex may be used as an antioxidant or a food supplement as an alternative to synthetic drugs.