Di Santo was born in Rocca Pia, Italy, and educated at the University of Rome. In Rome, Di Santo was a professional journalist as well as Press Secretary for the Italian Minister of Industry and Commerce. He was a member of the Family Services Association of Metro Toronto in 1974-75, and was an advisor to the Board of Community Workers at George Brown College. Di Santo was also a founding member as well as a federal executive on the Congress of Italian-Canadians in this period. He was also a founding member of the Italian-Canadian Benevolent Corporation. He is married to Toronto city councillor Maria Augimeri.
After the election, the Liberals and NDP signed a two-year pact which ended forty-two years of Progressive Conservative rule. After leaving the legislature, Di Santo was appointed director of the Office of the Worker Adviser.
The New Democratic Party won a majority government under Bob Rae's leadership in the 1990 provincial election, and Di Santo was appointed as chair of Ontario Workers' Compensation Board in 1991. During his tenure as chair, he implemented progressive policies, such as the non-rebuttable presumption that workers exposed to asbestos in the workplace be compensated for their injuries/illnesses - a novelty at the time. In 1994, Rae transferred Di Santo to the Liquor License Board of Ontario.
In 1992, Di Santo was President and founder of Casa Abruzzo, a non-profit for independent seniors.