Opuntia ficus-indica Mill fruit and cladodes are a source of mucilage, a carbohydrate complex, as well as of phytochemicals and other nutrients, useful in the food industry. Despite the environmental-based composition variability studied, there is no information on its seasonal variability, which is particularly important for its industrial use. In this study, some technological, nutritional, and bioactive properties of O. ficus-indica Mill cladodes mucilage were analyzed during the seasonal growth period. Total proteins did not change during the whole period and the lipid content significantly decreased from winter to the onset of summer. The fatty acid profile showed high levels of palmitic (16:0), oleic (18:1n9), and linoleic (18:2n6) acids and that the polyunsaturated fatty acid class (PUFA) is the most abundant fatty acid class, which showed a significant increase during the growth period. In this class, the presence of 20:5n-3 (EPA) and 22:6n-3 (DHA), two of the most important human nutrition essential fatty acids, is worth noting as well as the positive effect of the omega-3 series founder, α-linolenic acid 18:3 n-3. Total polyphenol values indicated that extract quality changes with the sampling period and is not closely related to the total extract yield. All the descriptors of the antioxidant power seem to indicate that the best properties are exhibited during the summer. The principal component analysis can significantly help identify the technological, nutritional, and bioactive factors that make it possible to distinguish the quality of O. ficus-indica Mill mucilage, in order to harvest it in the most appropriate season.