The application of environmentally friendly technologies, such as phytoremediation, for contaminated soil remediation and biofuel generation should be one of the goals of sustainable development. Phytoremediation is based on the use of plants and their associated microorganisms to clean contaminated soils, resulting in a positive impact on the environment and the production of biomass that can be utilized for biofuel production. Combining phytoremediation with advanced thermochemical conversion technologies like thermo-catalytic reforming process (TCR) allows for the production of high-quality biochar, bio-oil comparable to fossil crude oil, and hydrogen-rich syngas. This study presents a full-scale phytoremediation experiment conducted at a former oil storage site using energy crops like Jerusalem artichokes (Helianthus tuberosus), where the biomass was later converted into biofuel and other by-products using lab-scale technology. Significant and promising results were obtained: (i) within two years, the initial total petroleum hydrocarbons (TPH) contamination level (698 mg/kg) was reduced to a permissible level (146 mg/kg); (ii) the yield of the harvested Jerusalem artichoke biomass reached 18.3 t/ha dry weight; (iii) the thermochemical conversion produced high-quality products, such as a thermally stable oil a higher heating value (HHV) of 33.85 MJ/kg; (iv) the two-year phytoremediation costs for the rejuvenated soil amounted to3.75 EUR/t.