The present study aimed to examine the potential anticancer properties of fixed oil obtained from Maltese mushroom (Cynomorium coccineum L.), an edible, non-photosynthetic plant, used in traditional medicine of Mediterranean countries to treat various ailments and as an emergency food during the famine. We investigated the effect of the oil, obtained from dried stems by supercritical fractioned extraction with CO2, on B16F10 melanoma and colon cancer Caco-2 cell viability and lipid profile. The oil, rich in essential fatty acids (18:3n-3 and 18:2n-6), showed a significant growth inhibitory effect on melanoma and colon cancer cells. The incubation (24 h) with non-toxic oil concentrations (25 and 50 μg/mL) induced in both cancer cell lines a significant accumulation of the fatty acids 18:3n-3 and 18:2n-6 and an increase of the cellular levels of eicosapentaenoic acid (20:5n-3) with anticancer activity. Moreover, the oil exhibited the ability to potentiate the growth inhibitory effect of the antitumor drug 5-fluorouracil in Caco-2 cells and to influence the melanin content in B16F10 cells. The results qualify C. coccineum as a resource of oil, with potential benefits in cancer prevention, for nutraceutical and pharmaceutical applications.