The thermal recovery of heavy oil is an energy-intensive process with serious soil contamination due to its low energy efficiency and refractory petrolic/metallic pollutants emissions. In this work, a thermoconductive lignin-based hydrogel CaLS-CTS/h-BN was designed and synthesized for thermal energy conservation and soil self-remediation in thermal recovery, as a profile-control and oil-displacement agent. From experimental results, with the assistance of CaLS-CTS/h-BN gel, the thermal efficiency and cumulative oil-steam ratio of steam flooding were enlarged by 260% and 293% (up to 41.3% and 0.36), as input energy declined (reduction ratio 84.8%) from 15.08 kJ·(mL oil)−1 to 2.29 kJ·(mL oil)−1, through improving heating profile and strengthening heat transfer. Meanwhile, the rapid biodegradation of CaLS-CTS/h-BN biogel alleviated the formation damage and preserved subsequent productivity. On the other hand, after application of CaLS-CTS/h-BN gel, the natural degradation ratio of petroleum pollutants in soil was increased by 254% up to 46% due to the bio-stimulation and bio-ventilation effect of the biogel. Heavy metal content of oilfield soil was reduced by 35.8 wt% (from 17.3 g·(kg soil)−1 to 10.9 g·(kg soil)−1) with multiple heavy metal contaminants (including Cd, Cr, Cu, Zn, Mn, Pb and Fe) chelated and immobilized by the biogel. This study offered a green adjuvant agent for cleaner production of heavy oil.