The team, that will be based in the USA, will have two cars competing at the American Le Mans Series from March.
"I have had a passion for motorsport since I was a young boy growing up in Italy," said Del Piero on his official website.
"I am thrilled at the opportunity to team with Patrick. We expect to compete at a very high level and our central focus will be on winning world championships."
Dempsey added that Del Piero's "leadership skills" will be important for the team.
"We are excited to join forces with Alessandro and compete at the highest levels of racing," he said.
"Alessandro's passion for winning and leadership skills will be invaluable and he will play an important role in the development and direction of the team."
Dempsey is best known for his role on American television medical drama Grey's Anatomy.