Deuterated compounds have important applications, especially in the pharmaceutical field. Hence, the development of new and straightforward synthetic methods for the construction of deuterated compounds is becoming more and more attractive. We describe here a copper-catalyzed hydroxymethylation of aryl olefins with CO and D2 as the source of hydroxymethyl group. Various multideuterium 1,1,2,3-d4-labeled alcohols were produced directly. Mechanistic investigations established that the hydroxymethylation reaction proceeds via an in situ-generated carbon carbene intermediate.