Facing rising global food demand in a sustainable way is a great challenge of modern agriculture. Thus, the increase of crop productivity and resilience in an adverse climate scenario is urgently needed. Fungal endophytes have been described as potential biological tools to improve plant yield and tolerance to biotic and abiotic stresses; however, their application in agriculture needs further research. The fungal endophyte Colletotrichum tofieldiae strain Ct0861 establishes a mutualistic interaction with Arabidopsis thaliana, promoting plant growth and silique production at low phosphate conditions. Until now, its ability to colonize and confer benefits to other plant species remained unexplored. Here, we show that Ct0861 colonizes and promotes growth in vitro of maize (Zea mays L.) and tomato (Solanum lycopersicum L.) seedlings, resulting in significantly larger shoot length and weight. Greenhouse and field experiments in optimal nutritional conditions showed an increase between 12% and 22% of yield in both tomato and maize. The inoculated plants were not suffering from phosphate starvation, which points at different modes of action not elucidated yet. These results indicate that the beneficial effect of Ct0861 may extend to other plant species of economic importance, making Ct0861 a potentially valuable inoculant.