Titanium and its alloys are commonly used for dental implants prosthetics owing to their high biocompatibility and corrosion resistance. The corrosion resistance of these materials is related to the presence of the protective oxide film on the surface. However, various reactive oxygen species are present during inflammation, which can alter the passive film, resulting in the degradation of the titanium implants. Using corrosion inhibitors is one of the most common methods to prevent corrosion in metal and alloys. This research examined the effect of ethanolic extract of propolis on the corrosion behavior of titanium biomaterials (Ti and Ti-6Al-4V) in simulated oral cavity conditions without inflammation, with moderate or strong inflammation. This study was carried out by electrochemical techniques (open circuit potential measurement, linear polarisation, and potentiodynamic polarisation measurement), while the specimen’s surface was examined using an optical microscope. The results show that in simulated conditions of the oral cavity without and with moderate inflammation, the ethanolic extract of propolis inhibits Ti corrosion. In contrast, in simulated conditions of the oral cavity with strong inflammation, it promotes Ti corrosion. The ethanolic extract of propolis reduces corrosion of Ti-6Al-4V alloy in simulated oral cavity conditions, both without and with inflammation. The maximal inhibitory efficiency of ethanolic extract of propolis was for the Ti-6Al-4V alloy in simulated conditions of the oral cavity without inflammation, but inhibition efficiency decreased as the degree of inflammation increased. The results show that the tested ethanolic extract of propolis can be used as a corrosion inhibitor for the protection of Ti and Ti-6Al-4V alloy under the tested conditions.