The dissertation deals with the development of new metal processing technologies that enable to control and improve the microstructure and properties of the metals. Laser treatment is one such modern technique. The dissertation aims to determine the laser processing effect on the surface of a thin sheet of non-alloy structural steel. The research aims to solve one of the critical problems in diversifying the use of thin-sheet steel products in the industry by developing laser-processing technology for the creation of structural strengthening ribs, which can significantly affect the overall strength and stiffness of metal parts. The proposed solutions will help solve the problems of using thin-sheet metal products in the industry by increasing the stiffness with preserving the original design parameters (e.g., the product’s size, shape, and weight). This will save production time and resources due to the reduced number of technological and maintenance operations compared to traditional methods of increasing the stiffness of thin-sheet metals, where designing methods are based on the relationship between a construction geometry and its stiffness. The introductory chapter discusses the research aim and objectives. It also describes the research methodology, its scientific novelty, and the practical significance of the results. The introduction closes by presenting the author’s publications and conference papers on the dissertation’s topic and structure. The first chapter reviews the existing methods of increasing the hardness and stiffness of thin-sheet steel products. It also overviews the microstructure and the possibility of increasing the mechanical strength and hardness of the non-alloy steel. At the end of the chapter, the conclusions of the literature review are formulated, and the essential tasks of the dissertation are specified. The second chapter describes the materials and laboratory equipment used in the research work. This includes the methodology of microstructure analysis, mechanical properties testing, surface laser processing technology, calculating laser processing parameters, and modeling bending and tensile cases. The third chapter presents the results of the analysis of surface layer microstructure and phase composition, mechanical properties, calculation and selection of laser processing parameters, modeling of bending and tensile of treated thin-sheet samples, analysis of the importance of laser processing depth, and direction of processing, geometry, and direction of processing, and location of reinforcement areas. Six articles on the topic of the dissertation have been published, and the research results have been presented at nine scientific conferences in Lithuania and abroad.