Tannic and gallic acids, extracted from Chinese gallnut, were applied as copigments to bog bilberry syrup wine with two different mass ratios of 1:2.5 and 1:6 of anthocyanin to copigment. The effect of copigmentation on anthocyanins and the changes in non‐anthocyanin compounds and color characters during 6 months of aging were studied. Addition of copigment significantly helped to retain redness while reduced increase in the yellow shade and lightness. After 6 months of aging, the syrup wines with added copigments had 1.4–1.8 times higher total anthocyanin content compared to the control. The percentage of polymeric anthocyanins in copigment treated wines was lower than in control wine. Oppositely, the copigment treated wines possessed a higher percentage of copigmented anthocyanins than the control. The highest value of redness, the lowest percentage of polymeric anthocyanins and the highest percent of copigmented anthocyanins were presented in the wines treated with a high dosage of gallic acid.