Petunidin (Pt), like Europinidin and Malvidin, is derived from Delphinidin and is an O-methylated anthocyanidin of the 3-hydroxy type.

It is a natural organic compound, a dark-red or purple water-soluble pigment found in many red berries including chokeberries (Aronia sp), Saskatoon berries (Amelanchier alnifolia) or different species of grape (for instance Vitis vinifera, or muscadine, Vitis rotundifolia), and also part of the pigments responsible for the petal colors in many flowers.

This pigment gives the Indigo Rose tomatoes the majority of their deep purple color when the fruits are exposed to sunlight.

Petunidin could form in the exocarp of fruits from delphinidin, with an anthocyanin flavonoid O-methyltransferase (Catechol-O-methyl transferase) catalyzing the B-ring methylation and S-Adenosyl-L-methyl-3H methionine being the methyl group donor.

Glycoside forms of petunidin are present in grape.