Molinari, who made his debut in the 2010 edition when Europe regained the trophy in Wales, joins brother Edoardo Molinari (42), Spaniard Jose Maria Olazabal (57), Belgian Nicolas Colsaerts (40) and Denmark's Thomas Bjorn (52) as vice captains.
"I started the year hoping to be there as a player, but it is still a great honour to be there as a vice captain," Molinari, who won the 2018 British Open, said.
"I got a phone call from Luke asking if I was interested and obviously it was a clear answer from me. He is assembling a really good team of people.
"...It's a Ryder Cup which is particularly close to my heart being played in Rome so I will do whatever I can to help Luke and the team and hopefully bring the trophy back to Europe."
The United States won the last Ryder Cup in Wisconsin last year. Europe have not lost a Ryder Cup on home soil since a 15-13 defeat at The Belfry in England in 1993.
The Ryder Cup will be held from September 26th - October 1st.
