Seseli tomentosum Vis. belongs to the family Apiaceae. The species of this family are known for the content of essential oils and other specialized plant metabolites, which is why members of this family are the subject of numerous scientific studies and applications in folk medicine. As an endemic species of the coastal area of the Dinarides, the species S. tomentosum Vis. is a poorly researched species and we find no scientific papers describing its biological activity. In this study, the antifitovirus activity of hydrolates and methanolic extract of S. tomentosum, as well as their antiproliferative effect on cancer and healthy cell lines were investigated. Although the application of the hydrolate and methanolic extract did not inhibit the development of local viral infection caused by the tobacco mosaic virus, the hydrolate effectively reduced the virus concentration in the systemically infected plant host. The obtained results indicate that this plant species has significant anti-phytovirus potential, which indicates the possibility of using aromatic plant species for the development of new, natural anti-phytovirus preparations. Methanolic extract of the species Seseli tomentosum Vis. showed a significant antiproliferative effect on cervical cancer cell lines (Hela) and osteosarcoma (U2OS), while on colon cancer cells (HCT116) and a healthy retinal epithelial pigment cell line (RPE1) it showed a weak effect. Further in vivo and clinical trials are needed to examine the feasibility of using methanolic extract of Sesseli tomentosum Vis. as a natural chemotherapeutic.