For the first time, the full prototype of the ITER Hard X-Ray (HXR) monitor (HXRM) system has been successfully tested in a tokamak environment during the experimental campaign in the ADITYA Upgrade tokamak located at the Institute for Plasma Research. Unlike conventional HXR diagnostic systems operating in the existing tokamaks, the ITER HXRM is uniquely designed for robustness. In the HXRM system, the UV (Ultraviolet) photons from the scintillator are guided by the optical components to the PMT (Photomultiplier Tube). This approach introduces significant optical attenuation that has a direct impact on the characteristics of the PMT signal. As a result, digital pulse processing algorithms and the I&C (Instrumentation and Control) electronics need reconsideration to work correctly. The initial validation of the HXRM system design was carried out in the laboratory at the Department of Microelectronics and Computer Science, Lodz University of Technology, where the full prototype of the ITER HXRM system was established. The laboratory test validated the design considerations and aided the development of the I&C components. However, the functionality of the system has never been tested in the tokamak environment. The HXRM prototype setup was integrated into the ADITYA Upgrade tokamak and operated during plasma discharges. The data obtained from the plasma discharge allowed verification of the I&C electronics and methodology of the signal transmission, as well as validation of the developed PMT signal simulations. Several test configurations have been tested on the ADITYA Upgrade tokamak, and the preliminary results and observations are reported herein.