Energy transition has become the lead focus of the European Union (EU) agenda. The introduction of European Green Deal (EGD) has further raised the targets regarding greenhouse gas emissions, Renewable Energy (RE) and Energy Efficiency (EE) and strengthened legislation concerning the circular economy and biodiversity. Forest biomass energy has been at the forefront of the EU policy-making. In Central and Eastern Europe (CEE), where the forest biomass is mainly used for domestic heating in the form of round-wood, the issue of AQ has a significant role in the energy transition agenda. The burning of round-wood in old low-efficiency stoves cannot produce sufficient energy while exposing people to indoor and outdoor pollution. Moreover, the Particulate Matter (PM) from wood burning is associated with multiple health conditions. The research aims to understand the impact of the forest bio-energy policy mix on EP; hence the following research question is formulated: How is the forest biomass energy policy mix affecting energy poverty alleviation in Sofia, Bulgaria? The case study approach is suited to answer the main research question. Furthermore, the case study approach allows for in-depth exploration of complex issues and uses multiple research methods. The theoretical framework of the research is based on the policy mix conceptualisation proposed by Rogge and Reichardt (2016). Rogge and Reichardt define three building blocks of the policy mixes: elements, process and characteristics. The conflicts existing between the national level policy instruments and the rest of the policy mix result in vertical and horizontal inconsistency. Nevertheless, synergies between the EU instruments and the appliance change programs result in synergies. The lack of capability of the local and national institutions and the perceptions conflict indicate a lack of policy mix coherence. At the same time, the policy mix does not have any instruments to cover market failures exposing households to higher energy cost and include policy instruments outside the national energy plans indicating a lack of comprehensiveness. While the lack of consistency, coherence and comprehensiveness have some positive impact on energy cost, thus reducing energy poverty, the conflicts in the policy mix are sustaining the use of traditional fuels. Overall, in the situation of surging energy prices, the forest bio-energy policy mix is sustaining the EP; however, in the case of lower energy costs, the existing conflicts constitute a significant obstacle in alleviating EP in Sofia. The evaluation of the impact of the policy mix on energy poverty in Sofia shows that the lack of constancy, coherence and comprehensiveness and credibility does not always lead to adverse effects on the energy poverty indicators. Nevertheless, the results support the findings of other articles focusing on the impact of the energy transition on energy poverty and that the way to achieve energy poverty alleviation is to strive for consistent, coherent and comprehensive energy transition policies. In terms of the policy mix concept, the study shows the need for further empirical research on the multi-dimensional policy mixes and more emphasis on the instrument’s design features.