In this paper, a novel approach for condition monitoring of de-link capacitors in modular multilevel converters (MMCs) is proposed. The solution is intended for flexible alternating current transmission systems (FACTS) and high voltage direct current (HVDC) applications. The proposed technique does not require any current measurements and solely relies on voltage measurements that are already available in MMCs. The independence from current measurements simplifies the estimation process and reduces the uncertainties that may arise from current sensors. Experimental results demonstrate an overall estimation error of less than 1% when applying the proposed technique, which is similar to the error produced by methods that use current measurements for condition monitoring.