The global production quantity and the utilisation area harvested for the cultivation of tomatoes have significantly increased in the last three decades. Europe still plays an important role in the production of tomatoes, accounting for 12% of global production in 2020. Tomato production can be divided into greenhouse/soilless production and open field production. Greenhouse/soilless tomato production is mostly developed in northern Europe, and open field production in southern Europe. Soilless cultivation serves to improve control of the growing medium and to avoid any likely problems for watering and maintaining proper nutrient concentrations. Beneficial soil microorganisms, particularly arbuscular mycorrhizal fungi (AMF), are increasingly being recognized as key elements of an agro-ecological approach to agricultural production. The use of these beneficial microorganisms on soilless tomato production may improve plant performance and reduce biotic and abiotic stress occurring during production with a consequent decrease of chemicals and increase of sustainability of the production system. In this paper, we tested different substrates composed of coconut fiber and bagasse (S1 to S4) and beneficial microorganisms (AMF, Pseudomonas fluorescens and Trichoderma harzianum), selecting the most suitable system for the soilless production of tomatoes. Our results showed that substrates S1 (100% coconut fiber) and S2 (66% coconut fiber + 33% bagasse) complementarily used with the consortium of “AMF IP21 + Trichoderma harzianum + Pseudomonas fluorescens IPB04” seem to be the “best formulation” for this purpose. That confirmed the feasibility of the development of recycled material (coconut fiber and bagasse)-based substrates together with soil microorganisms (AMF and beneficial bacteria) for soilless tomato production.