 Cavagnago is first mentioned in 1270 as "Cavagnago".In the early 17th century, the hamlets of Segno, Mascengo and Codaghengo formed the village of Cavagnago which was a "Degagna" of the old "Vicinanza" of Giornico.In the Middle Ages, Cavagnago and Sobrio both worshiped at the 13th-century Chapel of St. Ambrose from Segno.