In the present paper we analyse the validity and nomenclatural status of the names of 16 taxa (eight species, four interspecific hybrids, one subspecies and three varieties) in Macaronesian Sonchus described or collected by E. R. Sventenius. As there is much controversy regarding their validity, mainly concerning the proper indication of the types and their location, we conducted a general revision of exsiccata, collected by Sventenius and kept at ORT, GB and BC, in order to locate possible type material. As a result, we located five holotypes, designated six lectotypes (four of which are illustrations), two neotypes and two epitypes, and located six isotypes and one paratype. We propose accepting the validity of most of Sventenius's names in the group with the exception of those whose protologue includes more than one gathering. Because except for S. ortunoi Svent. the taxa have valid names subsequently published by L. Boulos, we introduce a valid name for S. ortunoi here. Furthermore, we indicate legitimate names in the more widely circumscribed Sonchus that is now recognized based on recent phylogenetic reconstructions; in addition, we introduce the new combinations S.×rupicola (Svent.) A. Santos & Mejías and S.×decipiens (Svent.) A. Santos & Mejías.