Beneficial microorganisms play a pivotal role in the invasion process of exotic plants, including arbuscular mycorrhizal fungi (AMF) andBacillus. However, limited research exists on the synergistic influence of AMF andBacilluson the competition between both invasive and native plants. In this study, pot cultures ofAgeratina adenophoramonoculture,Rabdosia amethystoidesmonoculture, andA. adenophoraandR. amethystoidesmixture were used to investigate the effects of dominant AMF (Septoglomus constrictum, SC) andBacillus cereus(BC), and the co-inoculation of BC and SC on the competitive growth ofA. adenophora. The results showed that inoculation with BC, SC, and BC + SC significantly increased the biomass ofA. adenophoraby 14.77, 112.07, and 197.74%, respectively, in the competitive growth betweenA. adenophoraandR. amethystoides. Additionally, inoculation with BC increased the biomass ofR. amethystoidesby 185.07%, while inoculation with SC or BC + SC decreasedR. amethystoidesbiomass by 37.31 and 59.70% compared to the uninoculated treatment. Inoculation with BC significantly increased the nutrient contents in the rhizosphere soil of both plants and promoted their growth. Inoculation with SC or SC + BC notably increased the nitrogen and phosphorus contents ofA. adenophora, therefore enhancing its competitiveness. Compared with single inoculation, dual inoculation with SC and BC increased AMF colonization rate andBacillusdensity, indicating that SC and BC can form a synergistic effect to further enhance the growth and competitiveness ofA. adenophora. This study reveals the distinct role ofS. constrictumandB. cereusduring the invasion ofA. adenophora, and provide new clues to the underlying mechanisms of interaction between invasive plant, AMF andBacillus.