Bacillus subtilis strain GB03 enhances growth and photosynthesis in the model plant Arabidopsis thaliana and several crop plants. In the present study, the effects of seed soaking with GB03 suspension culture and its volatile organic compounds on seed germination of Codonopsis pilosula (Franch.) Nannf. were investigated, and soil-grown C. pilosula seedlings were assayed to measure growth and photosynthetic capacity after soil inoculation with GB03. Both seed soaking with GB03 suspension culture and the presence of volatile organic compounds enhanced seed germination, especially seed germination vigour. GB03 significantly improved shoot and root length, branching, plant biomass (whole plant fresh and dry weight), leaf area and chlorophyll content in C. pilosula seedlings after 20, 40 and 60 days of soil inoculation. GB03 significantly enhanced transpiration rate, stomatal conductance and net photosynthetic rate, but decreased intercellular CO₂ concentration. This study provides insight for the application of selected bacteria to improve biomass in Chinese herbal crops.