Exploiting extra-heavy crude oil and converting it to operational products is considered a challenging process in the industry due to the difficulty in processing this kind of crude oil. So, in the present study, viscosity reduction of extra-heavy crude oil is inquired using nanocatalysts. This is the first study that investigates and juxtaposes the results of viscosity reduction of extra-heavy crude oil based on direct heating and microwave radiation as the indirect heating source at the presence of ZSM-5 catalyst as well as silica, clay, and synthesized nickel oxide nanocatalysts in order to facilitate the process of extra-heavy crude oil upgrading. The results illustrate that nanocatalysts have a fundamental impact on the viscosity reduction of extra-heavy crude oil. According to the findings, nanosilica represents the best efficiency among others as it makes a 98.3% reduction in the extra-heavy crude oil viscosity. Besides, the application of microwave radiation in the upgrading of extra-heavy crude oil leads to an incredible reaction duration reduction as approximately 60% of sample oil viscosity is reduced in just 90 seconds. Analysis of upgraded oil reveals that adding excess nanocatalyst to the extra-heavy crude oil actuates an efficiency reduction due to the agglomeration of nanoparticles. Finally, the findings offer appealing information for the enhancement of upgrading processes in the industry.