Phosphate-solubilizing bacteria (PSB) are a group of organisms that solubilize fixed forms of phosphorus, making it available for the plant growth. The effect of three PSB strains, called PSBMi, PSBHc and PSBVa, on growth of pitahaya seedlings (Hylocereus undatus) was studied in a growth chamber. The results indicated that plant stem diameter, plant height, plant total dry weight and root length were greatest in pitahaya seedlings inoculated with PSBMi. The increase in these plant growth variables was 52.40, 34.71, 23.31 and 30.14% with respect to the control pitahaya seedlings not inoculated. The present study showed the potential of P-solubilizers on pitahaya seedling growth. However, further research is needed to understand the specific mechanisms involved in the positive effects of PSB on pitahaya plant growth and to verify these results under field conditions.