Peonidin is an O-methylated anthocyanidin derived from Cyanidin, and a primary plant pigment.

At pH 2.0, peonidin is cherry red; at 3.0 a strong yellowish pink; at 5.0 it is grape red-purple; and at 8.0 it becomes deep blue; unlike many anthocyanidins, however, it is stable at higher pH, and has been isolated as a blue colorant from the brilliant "Heavenly Blue" morning glory (Ipomoea tricolor Cav cv).

By far the greatest dietary source of peonidin is raw cranberries, which contain 42 mg per 100 g of fruit.

[citation needed] Blueberries, plums, grapes, and cherries also contain significant amounts, ranging from 5 to 12 mg/100 g. Only fresh fruit has been shown to contain significant peonidin; frozen blueberries have been shown to contain almost none.

Specifically, the amount of phenolic compounds in cranberries has been found to be inversely correlated with fruit size and crop yield.