Continental margin sediments are an important biogeochemical reactor, where 90% of organic matter (OM) is deposited and remineralized. OM remineralization proceeds from the use of O₂, NO₃, Mn(IV) oxides, Fe(III) oxides, sulfate, and finally CO₂ according to the gains of free energy yield, forming an ideal redox sequence. Differentiating various diagenetic pathways and their relative contributions to OM remineralization is of ecological importance for understanding energy partitioning and carbon cycling, and of biogeochemical importance for understanding the cycling of iron, sulfur, phosphorus, and redox-sensitive trace compounds. The main characteristics of diagenetic pathways of OM degradation and their relative contributions, particularly dissimilatory reduction of Fe(III) and Mn(IV) oxides, are reviewed. Generally, in pelagic deep sediments, aerobic respiration is the only important pathway for OM degradation; in continental margin sediments, however, anaerobic pathways coupled to dissimilatory reduction of Fe(III)oxides and sulfate are mainly responsible for OM degradation, with sulfate reduction accounting for averagely (62±17)%. From pelagic deep-sea to continental margin sediments, lateral zonation of the relative contributions of aerobic respiration and sulfate reduction, respectively, to carbon mineralization can be observed. Recent reaction-transport modeling indicates that global-scale contributions of aerobic respiration, denitrification, dissimilatory Fe(III) reduction, and sulfate reduction to OM degradation are 15%,6.2%,2.8%,and 76%, respectively.