Within carbon fiber manufacturing, the stabilization process is the most time- and energy-intensive process due to the complexity of chemical structure transformation. Therefore, optimization is strictly required to enable cost-efficient stabilization processes. For the first time, a hybrid semi-parametric model for continuous stabilization is developed to prognose stabilization progress and density of the stabilized fiber. The proposed model takes the process parameters like dwell time, stabilization temperature, and fiber stretching as well as precursor properties, such as fiber density, into account. Finally, the proposed hybrid semi-parametric model offers a novel plant-transferable optimization solution for model-based energy optimization in the stabilization process.