Azooxanthellate cold-water corals (CWCs) are globally widespread and have commonly been found in areas of active fluid seepage. The relationship between the CWCs and these fluids, however, is not well understood. This study aims at unravelling the relationship between CWC development and hydrocarbon-rich seepage in the Pompeia Province (Gulf of Cádiz, Atlantic Ocean). This region comprises mud volcanoes, coral ridges and fields of coral mounds, which are all affected by the tectonically driven seepage of hydrocarbon-rich fluids. Rate and type of seepage (i.e. focused, scattered, diffused, eruptive), however, is tightly controlled by a complex system of faults and diapirs. Early diagenetic carbonates from the currently active Al Gacel MV exhibit δ 13 C-signatures down to −28.77 ‰ VPDB, indicating biologically derived methane as the main carbon source. The same samples contained 13 C-depleted lipid biomarkers diagnostic for archaea such as crocetane (δ 13 C down to −101.2 ‰ VPDB) and PMI (δ 13 C down to −102.9 ‰ VPDB), evidencing microbially mediated anaerobic oxidation of methane (AOM). This is further supported by next generation DNA sequencing data, demonstrating the presence of AOM related microorganisms (ANME archaea, sulfate-reducing bacteria) in the carbonate. Embedded corals in some of the carbonates and CWC fragments exhibit less negative δ 13 C values (−8.08 to −1.39 ‰ VPDB), pointing against the use of methane as carbon source. Likewise, the absence of DNA from methane- and sulfide-oxidizing microbes in a sampled coral does not support a chemosynthetic lifestyle of these organisms. In the light of these findings, it appears that the CWCs benefit rather indirectly from hydrocarbon-rich seepage by using methane-derived authigenic carbonates as substratum for colonization. At the same time, chemosynthetic organisms at active sites prevent coral dissolution and necrosis by feeding on the seeped fluids (i.e. methane, sulfate, hydrogen sulfide), allowing cold-water corals to colonize carbonates currently affected by hydrocarbon-rich seepage.