Contamination of concrete with petroleum products occurs in industrial zones of oil extraction and processing enterprises, maintenance workshops, and filling stations. In countries with high temperatures during the spring-summer period — among which Kazakhstan is included — the chromatographic effect in oil-contaminated porous concrete promotes the vertical migration of oil masses, forming an explosive gas-air layer above solid surfaces, which poses serious risks at industrial facilities. In this regard, the aim of the present study was to develop a method for microbiological remediation of concreted surfaces and cracks contaminated with crude oil and petroleum products. The methods of infrared spectroscopy (IRS), scanning electron microscopy (SEM), as well as microbiological and taxonomic analysis were employed. It was established that the higher the porosity of the concrete, the smaller the area of oil stain spread on the surface and the greater the depth of penetration into the concrete mass. The penetration of oil into concrete occurs through micro- and nanocracks, which accounts for the difficulties associated with mechanical cleaning. Oil stain penetration proceeds through microcracks and pores of the concrete, with concurrent contamination of adjacent layers by fatty oils. The physicochemical composition of petroleum contamination in concrete is analogous to that of oil sludge with a low water content. The microflora of petroleum-contaminated concrete is represented by heterotrophic, hydrocarbon-oxidizing microorganisms of the genera Pseudomonas, Micrococcus, Bacillus, Penicillium, and Aspergillus. The spatial-structural distribution of these microbial groups shows that micromycetes and micrococcus — Micrococcus luteus and M. roseus — predominate on the surface of petroleum contaminations, while pseudomonads and bacilli are found within the bulk of the petroleum products. The role of hydrocarbon-oxidizing microorganisms and micromycetes in the biodegradation of petroleum-contaminated concrete is indisputable; however, thionic bacteria demonstrated the highest efficacy. The developed method of biological remediation of oil-contaminated concrete using thionic bacteria and oxalic acid enables concrete purification at a level of 95–97%.