This work addresses the challenges associated with depolluting brownfields or industrial sites, emphasizing the significant societal, financial, and environmental implications. Current depollution projects are often treated in an ad‐hoc manner, lacking a systematic and industrial perspective, despite the growing number of such projects. The proposed method advocates for a structured approach grounded in systems engineering principles, aiming to enhance collaboration among stakeholders, preserve knowledge, and facilitate the industrial transformation of depollution efforts. The method encompasses elements such as establishing a common vocabulary, employing modeling languages, implementing a double operational approach, providing supportive tools, and managing shared knowledge to improve project design, execution, and collaboration across multiple companies.