Leggio played for four years at Clarkson University, where he amassed a record of 59–29–12 with a .922 save percentage and allowed an average of 2.3 goals per game. In his college career, he had 8 shutouts.^[1] At Clarkson, Leggio helped Clarkson win the Eastern College Athletic Conference tournament championship in 2007 and the Eastern College Athletic Conference regular season title in 2008.

Leggio's pro career began with an amateur tryout with the Binghamton Senators of the American Hockey League at the end of the 2007–08 season, but for the 2008–09 season, he found himself with the Florida Everblades of the ECHL, sharing goaltending duties with Anton Khudobin on the way to winning the Brabham Cup as regular-season champions.

Leggio moved to Finland in 2009–10 to play for TPS in the top Finnish league, the SM-liiga. Leggio played in 30 games in his season in Finland. He also played in 7 of TPS's playoff games, leading the league in postseason goals against average at 1.57 and helping TPS to the league title.^[2]

On August 8, 2010, Leggio returned to the United States, signing as a free agent to a one-year contract with the Portland Pirates of the American Hockey League. Three months later, the Buffalo Sabres, the NHL team with which Portland is affiliated, converted Leggio's AHL contract to an NHL two-way contract, but kept Leggio in Portland.^[3] In 2010-11, he played 36 regular-season games for Portland and 9 in the postseason. Leggio was re-signed to the Sabres organization in June 2011, where he was assigned to theRochester Americans (Buffalo changed minor-league affiliations from Portland to Rochester in 2011). Leggio saw action in 54 games for Rochester in the 2011-12 season, winning a career-high 28, but he went 0-3 in the postseason.