The quest for renewable energy resources prompted researchers to find alternative feedstock for bioenergy programs without diverting the food crops for these purposes. The invasive terrestrial weeds pose a significant challenge to policymakers and farmers as chemical and mechanical tools are frequently utilized for their management, which seems costly and non-eco-friendly. The utility of weed biomass in renewable bioresource generation could be a sustainable and cost-effective approach. Terrestrial weeds such as Parthenium hysterophorus and Lantana camara have been significant problems in different land use systems worldwide. The high productivity, availability of green foliage and woody substances, and adaptability to the local environment proposed them as valuable sources of lignocellulosic biomass. Recent investigations suggested that such weeds could be effectively utilized for developing bioenergy sources (bioethanol, biomethane, biohydrogen, etc.), and woody substances could be a suitable feedstock for pyrolysis products. This chapter summarised the potential of Parthenium and L. camara biomass in bioenergy production under a waste-to-wealth approach system. Also discusses innovative, cost-effective and sustainable strategies for managing and mitigating weed biomass in the context of bioenergy production.