Before turning professional, DeFazio attended
Clarkson University where he played four seasons of
NCAA Division I men's ice hockey with the
Clarkson Golden Knights men's ice hockey team. After graduating from his senior year with Clarkson, DeFazio joined the
Pittsburgh Penguins affiliate teams, the
Wheeling Nailers of the
ECHL and the
Wilkes-Barre/Scranton Penguins to end the
2010–11 season. Wilkes-Barre signed DeFazio to a one-year AHL contract and was also given a try-out and attended Pittsburgh's NHL training camp for the
2011–12 season. On July 2, 2012, DeFazio signed as a free agent to a one-year, two-way contract with the
New York Islanders. A year later, though, DeFazio left the Islanders organization as a free agent and signed a one-year contract with the
Vancouver Canucks on July 12, 2013. In the
2014–15 season, DeFazio received his first NHL recall by the Canucks on November 9, 2014. He made his long-awaited NHL debut that night in a 2–1 shootout victory over the
Anaheim Ducks. DeFazio played in his second career game on November 11 against the
Ottawa Senators, where he collected the first shot of his career while playing 5 minutes and 49 seconds. On July 6, 2015, having left the Canucks as a free agent, DeFazio returned to the Eastern Conference by signing a one-year, two-way contract with the
Boston Bruins. In the off-season, DeFazio left the Bruins organization as a free agent and on July 25, 2016, he was signed to a one-year contract to continue in the AHL with the
Texas Stars. In the
2016–17 season, DeFazio compiled a career-best 47 points in appearing in every regular season game with Texas. After 6 seasons largely in the AHL, DeFazio as a free agent agreed to a one-year deal with Chinese club,
HC Kunlun Red Star of the
Kontinental Hockey League (KHL) on June 6, 2017. DeFazio left Kunlun for the following
2018–19 season, signing a year contract with
Lukko of the Finnish
Liiga, before returning for a second stint with Kunlun for the
2019–20 season. As a free agent during the
COVID-19 pandemic, DeFazio was later signed to a contract with the Czech Extraliga club,
HC Kometa Brno, on November 17, 2020. Scoreless in 6 games with Brno in the
2020–21 season, DeFazio left the ELH to be the final addition to German DEL club,
ERC Ingolstadt, on December 5, 2020. On June 9, 2022, DeFazio signed as a free agent to a one-year contract with fellow German club,
Schwenninger Wild Wings, for the
2022–23 season. DeFazio featured in every regular season game with the Wild Wings, collecting 10 goals and 21 points. Unable to help Schwenninger advance to the post-season, it was announced DeFazio would leave the club after his contract on March 9, 2023. ==Post-playing career==