Luigi Chiumiento ambushed his wife Raffaella Romano in Benevento town, and shot her at point-blank range as she sat in the driving seat of her car.
Chiumento then turned the gun on himself, police said.
The couple were in their forties and had three children aged between nine and 17.
Witnesses said Chiumiento and Romano had marital problems for some time but were not separated.
Women in Italy are among those at highest risk of being murdered by their partners, says a study by Britain's Lancet medical journal.