A blow-by gas filtration assembly fluidically connects to a vehicle engine system to receive blow-by gases and filter the suspended particles. A filtration assembly main body includes a filtration chamber and an outlet mouth. A filter group is radially crossable by blow-by gases from outside to inside, including a central cavity. A command group partially houses and supports on the main body operatively connected to the filter group to command the filter group in rotation. A support group supporting the filter group includes a bearing element with an outer fifth wheel sealingly engaging an outlet edge, an inner fifth wheel defining an outlet passage for filtered blow-by gases, and a hollow tubular member defining an outlet duct, including a bearing end operatively connected to the inner fifth wheel and a support portion extending from the bearing end, in the central cavity, mounting the filter group on the support portion.