Comprehensive Summary We develop an efficient visible‐light photoreodox‐catalyzed hydrodecarboxylation and deuterodecarboxylation of fatty acids for alkanes and deuterium alkanes. The key to the efficient transformation should attribute to the co‐catalysis of the suitable methoxy substituted acridine photocatalyst (Mes‐1,3,6,8‐tetramethoxy‐Acr‐3”,5”‐dimethoxy‐Ph) and the hydrogen atom transfer catalyst 4′,4′‐dimethyl diphenyldisulfane, possibly via facilitating of quenching the active alkyl radicals to overcome the competitive homocoupling products, olefins via the disproportionation, cracking products via the C—C bond β‐scission.