Search for alternative methods for the treatment of bacterial vaginosis has been growing, and probiotics being among them. The most well-known probiotic microorganisms are lactobacilli, which are naturally present in the vaginal microenvironment. Cocoa fermentation is a source of lactic acid bacteria, with lactobacilli being the most prominent. The aim of this study was to evaluate the antagonistic activity of Lactiplantibacillus plantarum 6.2 a strain of lactobacilli isolated from cocoa fermentation, and its cell-free supernatant on Gardnerella vaginalis. It was shown that Lpb. plantarum 6.2 and its supernatant, used at three concentrations, i.e., 40, 20 and 10 mg/mL, have a strong antagonistic activity against G. vaginalis, with a probable action of proteinaceous bacteriocins; the activity was lost after heat treatment. The ability to exclude and displace G. vaginalis from the adhesion site to vaginal HMVII epithelial cells was also demonstrated by the lactobacilli and the supernatant, with the latter showing a bactericidal effect. Thus, the Lpb. plantarum 6.2 strain presents itself as a good probiotic with potential to be used not only as a therapeutic alternative for vaginosis but also as a complement to existing therapies.