This study presents the results of a comparative environmental and economic Life Cycle Assessment (LCA) of biomass-to-bioenergy valorization scenarios integrated into the phytoremediation of dredged sediment using perennial reed Arundo Donax. A mathematical baseline was developed based on empirical data as a prerequisite for parametric life cycle inventory models for both economic and environmental assessments. The baseline enabled the estimation of bioenergy yields in various forms: solid, liquid, gas, and the eventual generation of green electricity that could potentially be obtained from biomass valorization per m3 of sediment during phytoremediation. The models were applied to assess the environmental and economic impacts of phytoremediation integrated into biomass valorization alongside conducting sensitivity and uncertainty analysis. Inferred from the comparative LCAs, it was concluded that the valorization of biomass, derived from phytoremediation, into bioenergy could partially or totally compensate for the environmental and economic impacts of phytoremediation. The model developed in this study is a general model applicable to different types of plants and phytoremediation scenarios along with biomass to bioenergy valorization schemes.