Streptococcus agalactiae (Group B Strep, GBS) infections in neonates are often fatal and strongly associated with maternal GBS vaginal colonization. Here, we investigated the role of a previously uncharacterized protein, BvaP, in GBS vaginal colonization. BvaP was previously identified as the most highly upregulated gene in the GBS A909 transcriptome when comparing vaginal colonization to growth in liquid culture. We found that expression of BvaP affects GBS adherence to extracellular matrix components and human vaginal epithelial cells and a ΔbvaP mutant was significantly decreased in its ability to colonize the murine vaginal tract. Cellular morphological alterations such as changes in cell shape, chain length, and clumping were also observed in a knockout mutant strain. Given its high expression in vivo, high degree of conservation among GBS strains, and role in vaginal colonization, BvaP may be an eligible target for GBS vaccination and/or drug therapy.