Retrofitting deteriorating structures is an essential and complex task that requires a careful balance between cost, risk, and the anticipated benefits of various retrofit strategies. As the structures age, the need for effective retrofitting strategies becomes increasingly urgent to ensure the safety, functionality, and longevity of these structures. The task of retrofitting necessitates a delicate balance between various factors, including cost, risk, and the projected benefits of different retrofit strategies. The complexities involved are further compounded by the uncertainties inherent in both the deterioration processes of structures and the effectiveness of potential retrofit interventions. In order to address these challenges, this paper introduces a probabilistic framework to optimize retrofit decisions using a risk-based real options analysis approach. The proposed framework leverages the concept of real options, which provides a structured method to incorporate flexibility into decision-making processes under uncertainty. The framework begins with a time-dependent risk assessment that evaluates the deterioration processes affecting the structural performance. This assessment is conducted both with and without the implementation of retrofit measures. By integrating the risk assessment process with real options analysis, the framework estimates the real option values associated with different retrofit scenarios. Subsequently, it formulates an optimization problem to maximize the real option value. This approach identifies the optimal retrofit method and associated application times. To demonstrate the practical application of the proposed framework, the paper presents a case study involving deteriorating reinforced concrete bridge columns. This case study investigates the effects of various parameters involved in the real options analysis on optimal retrofit planning.