The cathedral in Fidenza (a town once called Borgo San Donnino) is dedicated to him.

The Hieronymian Martyrology commemorates Domninus, but does not include any further information about him, and his feast day is cited as occurring on 9 October.

It is recounted that Domninus picked up his severed head and placed it on the future site of the cathedral of San Donnino.

His relics are enshrined in Fidenza Cathedral, adding some plausibility to the tradition that he suffered martyrdom in this region.

The ancient basilica at Fidenza, rebuilt in the 12th century, includes a sculpted frieze sub-divided into five scenes representing the life of the saint.