Bacterial vaginosis (BV) is the worldwide leading vaginal disorder among women of reproductive age. BV is characterized by the replacement of beneficial lactobacilli and the augmentation of anaerobic bacteria. Gardnerella vaginalis is a predominant bacterial species, but BV is also associated with other numerous anaerobes, such as Atopobium vaginae, Mobiluncus mulieris, Prevotella bivia, Fusobacterium nucleatum, and Peptoniphilus species. Currently, the role of G. vaginalis in the etiology of BV remains a matter of controversy. However, it is known that, in patients with BV, a biofilm is usually formed on the vaginal epithelium and that G. vaginalis is typically the predominant species. So, the current paradigm is that the establishment of a biofilm plays a key role in the pathogenesis of BV. This review provides background on the influence of biofilm formation by G. vaginalis and other anaerobes, from the time of their initial adhesion until biofilm formation, in the polymicrobial etiology of BV and discusses the commensal and synergic interactions established between them to understand the phenotypic shift of G. vaginalis biofilm formation to BV establishment.