Cynara cardunculus L. is a diploid (2n = 34) outcrossing perennial species, native to the Mediterranean basin, comprising the globe artichoke, the cultivated cardoon, and the wild cardoon. These species have potential as biomass, sugar, and oilseed crops. This paper aimed to study the genetic variability for sugar production and sugar composition in the roots of different C. cardunculus L. genotypes, in order to select those suitable for this specific purpose in the Mediterranean environment. At harvest the total biomass and root production, averaged for all genotypes, were 20.4 and 9.8 t DM/ha; they were influenced by genotype, with a CV of 37.4 and 38.5%, respectively. On average for all of the genotypes, the roots showed a total sugar content of 367 g DM/kg, with a CV of 17.1%; the main compound was inulin (85.0% of total sugars). The wild cardoon ‘SR1’ showed the highest total sugar content (470 g/kg DM). On average for all of the genotypes, the total sugar and inulin yields were 3.6 ± 0.20 and 3.0 ± 0.16 t/ha, respectively. It was possible to obtain total sugar yields higher than 4 t/ha in 6 genotypes (‘BH’, ‘VP’, ‘E438’, ‘L01’, ‘C2’, ‘P1’) of the 15 studied.