Lemon juice (LJ) was enriched with aronia concentrate (AC) in two different proportions (2.5 and 5%, v/v) to design new beverages rich in bioactive ingredients. The phytochemical composition (anthocyanins, flavanones, flavones, flavonols, and hydroxycinnamic acids) and stability of the beverages were analyzed by high-performance liquid chromatography with a diode array detector (HPLC-DAD), as well as color alterations and in vitro antioxidant activity (DPPH(*) assay). Results showed that, although anthocyanin degradation was higher than 90% after 60 days of storage, the new beverages retained an attractive red color. Also, the in vitro antioxidant activity of the new mixtures was 2-fold higher when 5% AC was added compared to pure LJ. Thus, an addition of only 5% AC could effectively increase the antioxidant properties of LJ, as well as improving certain organoleptic characteristics, rendering an interesting beverage in the growing market of food for health.