This article presents the results of experimental and numerical studies related to the evaluation of leakage from a static gasket with a geometrically structured sealing surface. The concept of this solution utilizes the so-called flow circulation effect within the microchannels formed on the sealing surface. The surface microstructure was designed to generate a partial reverse flow relative to the direction of the sealed medium, leading to increased flow resistance. Comparative experimental studies were conducted to analyze the relationship between leakage rate and contact pressure on both smooth and structured gasket surfaces. In addition, a CFD analysis was carried out to identify phenomena associated with the flow of the sealed medium through the gasket and to evaluate the impact of microgeometry within the flow gap on the flow resistance. On the basis of the experimental and numerical results, a significant improvement in tightness was observed with the application of a structured external sealing surface. Within the contact pressure range of 20 MPa to 40 MPa, the structured gasket exhibited leakage up to three orders of magnitude lower compared to the smooth surface gasket. The CFD analysis confirmed that the microgeometry increases the flow resistance, significantly reducing leakage.