Bioherbicides are the compounds containing biotic agents, mostly microorganisms and/or their metabolites released by them, which are capable to suppress the excessive growth of weeds. Invasive weeds are considered as most potential threat in agricultural field, water bodies, and bare lands than native weeds, as they are better competitor in many ways. Keeping in mind the adverse effect of synthetic chemical herbicides, bioherbicide should be grasped by the farmers as an alternative tool for invasive weed management and agronomy. Challenges are taken by scientist, researchers, and industrialist to protect crops and other native species from the destructions caused by invasive weeds in an eco-friendly manner. Challenges are also taken in securing worldwide acceptance of the bioherbicide and developing their future role as potential inundative weed control measure. Even so, the success rate of commercialized bioherbicide is relatively few. This chapter covers the background story of introducing fungi and fungal metabolites (mycoherbicide) as biocontrol tool, importance of choosing mycoherbicides, the contribution of fungi and their metabolites in our ecosystem, and how environmental factors can stimulate the production of fungal secondary metabolites. A detailed information about commercial mycoherbicide worldwide with the unrealized advantage of successful application of it as well as the probable factors limiting the success rate of commercialized mycoherbicides are also discussed in this chapter.