Natural compounds derived from higher plants can serve as new sources of antibacterial drugs with potentially novel mechanisms of action. Traditional medicine uses plant extracts to treat a variety of infectious disorders, including those caused by bacteria and fungi. Currently, there is a great demand for plant extracts with significant antibacterial activity. In this study, extracts from four plants—Lantana camara, Withania somnifera, Cetrariais landica, and Tribulus terrestris—were subjected to phytochemical screening, and in vitro antibacterial activity was evaluated. Phytochemical investigations revealed the presence of saponins, alkaloids, phenolics, flavonoids, carbohydrates, proteins, amino acids, glycosides, tannins, and terpenoids. The antimicrobial activities of the plant extracts were assessed using the disc diffusion method. They exhibited varied antimicrobial activities against gram-negative bacteria (E. coli and P. aeruginosa), gram-positive bacteria (B. subtilis and S. aureus), and fungi (C. albicans, A. niger, F. oxisporium, and F. solani). Lantana camara extract showed the highest phytochemical content and antimicrobial activity. These findings can be used in the pharmaceutical and alternative medicine industries to create natural bioactive compounds that are beneficial to human health.