Limestone has many uses in buildings, commonly employed as façade, paving, flooring, stair, and kerb. Slake durability and physico‑mechanical properties are key indicators in evaluating the quality of limestone for use in various parts of a building. Depending on the conditions of formation and the depositional environment, limestone may contain organic carbon (OC). The organic carbon may affect the slake durability and physico‑mechanical properties of limestone. In the present study, OC-free and the OC-bearing limestone samples were prepared. The slake durability indexes (SDI) and physico‑mechanical properties [including effective porosity (n), uniaxial compressive strength (UCS), and Brazilian tensile strength (BTS)] of the samples were measured. The results showed that the SDI, n, UCS, and BTS of samples are strongly influenced by the presence of OC. Compared with OC-free limestone, OC-bearing limestone shows a lower SDI, UCS, and BTS, while exhibiting higher n values. The adverse changes in n, SDI, UCS, and BTS are attributed to the formation of a sponge‑like texture in limestone due to the presence of OC, which consequently increases the n of samples. Based on the data analysis, when the use of OC-bearing limestone in a building is intended, it is essential to select samples with the lowest possible OC content.