The extensive use of agrochemicals to combat fungi, bacteria, nematodes, and insects in agriculture can cause severe soil and water contamination. A cleaner and eco-friendly alternative to minimize or avoid such contamination could be using biological agents. The fungus Trichoderma is present in most types of soil. It has a high tolerance to metals, and members of this genus have proven to be excellent biological control agents and plant growth promoters. Then, members of the Trichoderma genus are an excellent alternative to reducing harmful pesticides used in agriculture. Also, there is great potential for using Trichoderma species to produce metallic nanoparticles, which could reduce or eliminate the use of fungicides. Also, antimicrobial and catalytic properties of metallic nanoparticles have great potential for wastewater treatment. This chapter aims to describe the broad applications of Trichoderma to reduce contamination of our environment.