The aim of this work was to compare 'Nero' and 'Viking' aronia cultivars and to determine the optimum harvest dates of each cultivar for various utilizations. For this purpose, we characterized the changes in both aronia cultivars' physicochemical components over their harvest period and identified the correlations between them. Mean berry weight, dry matter, soluble solid content, antioxidant activity, and anthocyanin content of berries of both cultivars increased until the second and third weeks of September. They then began decreasing gradually, whereas total phenol content and condensed tannins kept increasing until 27 October. It was observed that berries of 'Nero' ripened 15 days earlier than those of 'Viking'. As a result, anthocyanin content of 'Nero' peaked earlier (25 August) than that of 'Viking'. The highest correlation (r = 0.75, P < 0.01) was found between anthocyanin and firmness; antioxidant activity was slightly correlated with total phenol content (r = 0.57, P < 0.01) and total anthocyanin (r = 0.49, P < 0.05). In terms of yield, the optimum harvest time for both cultivars was found to be the second week of September. Taking also into account the anthocyanin content, antioxidant capacity, and total phenol, the optimum harvest time was determined to be during the second and third weeks of September. On the other hand, the optimum harvest time for dry consumption was found to be during the first and second weeks of October.