The fungal parasite of nematode eggsPochonia chlamydosporiais also a root endophyte known to promote growth of some plants. In this study, we analysed the effect of nineP.chlamydosporiaisolates from worldwide origin on tomato growth. Experiments were performed at different scales (Petri dish, growth chamber and greenhouse conditions) and developmental stages (seedlings, plantlets and plants). SevenP.chlamydosporiaisolates significantly (P< 0.05) increased the number of secondary roots and six of those increased total weight of tomato seedlings. SixP.chlamydosporiaisolates also increased root weight of tomato plantlets. Root colonisation varied between different isolates of this fungus. AgainP.chlamydosporiasignificantly increased root growth of tomato plants under greenhouse conditions and reduced flowering and fruiting times (up to 5 and 12 days, respectively) versus uninoculated tomato plants.P. chlamydosporiaincreased mature fruit weight in tomato plants. The basis of the mechanisms for growth, flowering and yield promotion in tomato by the fungus are unknown. However, we found thatP. chlamydosporiacan produce Indole‐3‐acetic acid and solubilise mineral phosphate. These results suggest that plant hormones or nutrient ability could play an important role. Our results put forward the agronomic importance ofP. chlamydosporiaas biocontrol agent of plant parasitic nematodes with tomato growth promoting capabilities.