Background: Gouania longispicata Engl. (Family: Rhamnaceae) has been used for traditional medicine applications for the treatment of over 42 ailments including allergy, tooth decay, mastitis and syphilis. The common use of G. longispicata in traditional healthcare systems echoes its relevance in light of modern pharmaceutical perspectives. Aim: To determine the ethnobotany and antimicrobial activity of G. longispicata, which is traditionally used in Bwambara sub-county. Materials and Methods: A cross-sectional study was conducted from January to June 2018, using questionnaires to collect ethnobotanical data on Gouania longispicata Engl.Air dried powdered plant material was sequentially extracted using hexane, chloroform, methanol and water. Phytochemical screening and antimicrobial activity were done following standard procedures. Results: Phytochemical screening revealed the presence of flavonoids, cardiac glycosides, saponins, steroids, resins, and phenolic compounds in different plant extracts. Methanol fraction inhibited growth of all bacterial strains under study, while aqueous extract and aqueous fraction showed activity against the fungal strains under study and only one bacterial strain Streptococcus pneumoniae. The most susceptible microorganism was Streptococcus pneumoniae with MICs of 1.95 mg/mL for methanol fraction, 15.6 mg/mL for aqueous fraction and 31.25 mg/mL for aqueous extract. Conclusion: The local population has used G. longispicata to treat various ailments for a long time. The antimicrobial activities of the various extracts provide a baseline for its use in the treatment of various diseases. Toxicity and structure elucidation of the bioactive compounds in the various extracts need to be studied.