The use of plant growth-promoting microorganisms has emerged as a sustainable strategy to enhance the early establishment of agricultural crops. In this study, the effect of Methylobacterium sp. (SEMIA 658) on the early growth and biomass partitioning of soybean (Glycine max L.) and common bean (Phaseolus vulgaris L.) plants was evaluated by comparing two inoculation methods: sowing furrow and seed treatment. The experiment was conducted under greenhouse conditions in a completely randomized design, with three treatments and eight replications. At 25 days after emergence, shoot dry mass, root dry mass, and total dry mass were determined, along with biomass allocation indices and the relative gain compared with the control. Inoculation with Methylobacterium sp. promoted significant increases in the early growth of both crops. In soybean, total dry mass nearly doubled in the inoculated treatments, regardless of the application method. In common bean, a progressive increase in total biomass was observed, with a greater response in the seed treatment, associated with an increase in the fraction of biomass allocated to roots. The results indicate that Methylobacterium sp. (SEMIA 658) acts as a promoter of early plant growth by modulating both biomass accumulation and allocation, with responses dependent on crop species and inoculation strategy. These findings reinforce the potential of this microorganism as a bio-input for efficient and sustainable agricultural systems, particularly during the crop establishment phase.