To increase the ambition and effectiveness of a global coal phase-out, it is central to understand how one extraction regime – fossil fuel extractivism (FE) — was phased in. Doing so may make it possible to confront the actors dependent on and strengthened by the associated natural resource rents. Characterized by the large-scale, high-impact, export-oriented extraction of fossil fuels such as steam coal, the present paper traces the processes that led first to the phase-in and then to the entrenchment of FE in Colombia. Taking the case of large-scale coal extraction (LSCE) as an example, the paper analyzes the causal mechanisms allowing this activity to take deep roots in politics, society and the economy, with grave implications for the environment and culture of affected communities and the country as a whole. Drawing on different data sources (20 stakeholder interviews, policy and press documents, scholarly research, etc.), the paper adapted Palley’s (2017) notion of policy lock-in and lock-out via hysteresis to propose an entrenchment spiral as a potential mechanism leading to the current degree of coal and fossil fuel extraction entrenchment in Colombia. The paper concludes that the phase-in of LSCE and FE was facilitated by the combination of masking and securitization strategies used by an incumbency regime closely associated with state capture. As power dynamics shifted, asymmetric dependency relationships between mining companies and affected individuals, communities and governments at local, regional and national levels were gradually generated, leading to this sector’s seemingly inexpugnable position. That said, knowledge is power. Knowing how phase-in and entrenchment occurred and still happens can be an initial step towards confronting and even reversing it