Anthony DeAngelo left his hometown of Sewell, New Jersey at 15 to start his junior career with the Cedar Rapids Roughriders of the United States Hockey League. In his 28 games in Iowa, the young defenseman showed enough promise to become a second-round selection in the 2011 Ontario Hockey League Draft.
During the 2013–14 season, DeAngelo was suspended eight games by his Ontario Hockey League team, the Sarnia Sting, and league for making "a most inappropriate statement to a teammate". Despite this trangression, DeAngelo was considered to be a top prospect heading into the 2014 NHL Entry Draft.
On December 2, 2014, the Tampa Bay Lightning announced the signing of DeAngelo to a three-year, entry level contract. DeAngelo, has skated in 22 games this season with the Sarnia Sting of the Ontario Hockey League, recording seven goals and 27 points to go along with 52 penalty minutes. He currently ranks first in points and second in assists (20) among all OHL defensemen. DeAngelo led all OHL defensemen in points (71) and assists (56) last season. He has skated in 203 OHL games, all with the Sarnia Sting over four seasons, recording 37 goals and 179 points to go along with 248 penalty minutes. Additionally, he has appeared in 10 career OHL playoff games, putting up two goals and two assists. On January 8, 2015 the Sarnia Sting traded DeAngelo to the Sault Ste. Marie Greyhounds. The Greyhounds are believed to be making a push for the OHL championship, and a spot in the Memorial Cup Tournament.
On May 6, 2015, the Ontario Hockey League announced that DeAngelo was the recipient of the Max Kaminsky Trophy as the OHL's most outstanding defensemen. DeAngelo led all defensemen and finished 13th overall in OHL scoring with 89 points in 55 games played recording 25 goals and 64 assists with 25 multi-point games and a plus-minus rating of plus-34. He also became the fourth member of the Sault Ste. Marie Greyhounds to win the award. DeAngelo also captured the CHL Defenceman of the Year in the same season, as the top defensemen of the entire Canadian Hockey League.
After attending the Tampa Bay Lightning's NHL training camp, DeAngelo was assigned to begin his first professional season with AHL affiliate, the Syracuse Crunch. In the 2015–16 season, DeAngelo's offensive game made a smooth transition with the Crunch, contributing with 37 assists and 43 points in 69 games, to finish 7th league wide among blueliners.
At the 2016 NHL Entry Draft, DeAngelo was traded by the Lightning to the Arizona Coyotes in exchange for a second-round draft pick (Libor Hajek) on June 25, 2016. On November 8, 2016, DeAngelo made his NHL debut against the Colorado Avalanche at the Pepsi Center in a Coyotes 4-2 win. In addition to making his NHL debut, DeAngelo also recorded his first career NHL goal and point. On November 12, 2016, DeAngelo recorded his first career NHL assist against the Boston Bruins at Gila River Arena. On January 1, 2017, the National Hockey League announced that DeAngelo was suspended for three games, without pay, for violating Rule 40.4 (Physical Abuse of Officials). The incident occurred on December 31, 2016, in a game against the Calgary Flames at the Scotiabank Saddledome. At the time DeAngelo was given a game misconduct for abuse of officials. DeAngelo forfeited $14,388.90 as a result of the suspension, which went to the Players' Emergency Assistance Fund.
On June 23, 2017, DeAngelo, along with a first-round pick in the 2017 NHL Entry Draft (7th overall), was traded to the New York Rangers for center Derek Stepan and goaltender Antti Raanta.
DeAngelo competed with Team USA at the 2012 Ivan Hlinka Memorial Tournament.
On December 2, 2014, DeAngelo was named to Team USA's preliminary roster for the World Junior Championship tournament, which was held December 26 through January 5 in Toronto and Montreal.