Although peripheral B cell dysfunction in early HIV infection is established, how B cell subsets are altered by HIV infection is poorly understood. While investigating B cell subsets among individuals recently infected with HIV, we observe an accumulation of CD27-CD38+ B cells and find that these cells can directly facilitate HIV infection of primary CD4+ T cells in vitro. Comprehensive analyses of the phenotype, function, and transcriptome of the CD27-CD38+ B cell subset is conducted compared with memory and naive B cells. We find that the CD27-CD38+ B cells exhibit a transitional B cell phenotype and an extremely high turnover rate. Importantly, individuals with higher proportions of CD27-CD38+ B cells during early HIV infection tend to become rapid progressors in the chronic infection stage. In this study, we identify a peripheral transitional B cell subset that accumulates during early HIV infection and may contribute to disease progression.Keywords: B cell subset; HIV disease progression; early HIV infection; transitional B cells.