Carboxylic acids are readily available in both the natural and synthetic world. Their direct utilization for preparing organophosphorus compounds would greatly benefit the development of organophosphorus chemistry. In this manuscript, we describe a novel and practical phosphorylating reaction under the transition metal-free reaction conditions that can selectively convert carboxylic acids into the P-C-O-P motif-containing compounds through bisphosphorylation and the benzyl phosphorus compounds through deoxyphosphorylation. The strategy provides a new route for carboxylic acid conversion as the alkyl source, enabling highly efficient and practical synthesis of the corresponding value-added organophosphorus compounds with high chemo-selectivity and wide substrate scope, including the late modification of complex APIs. Moreover, this reaction also indicates a new strategy for converting carboxylic acids into alkenes by coupling this work and subsequent WHE reaction with ketones and aldehydes. We anticipate that this new transforming mode of carboxylic acids will find wide applications in chemical synthesis.