As a youth, Danault played in the 2005 and 2006 Quebec International Pee-Wee Hockey Tournaments with the Victoriaville Tigresminor ice hockey team. He later played junior ice hockey with the Victoriaville Tigres and Moncton Wildcats of the Quebec Major Junior Hockey League. He was selected 26th overall in the 2011 NHL Entry Draft by the Chicago Blackhawks. On March 30, 2012, he was assigned to the Blackhawks' American Hockey League affiliate, the Rockford IceHogs. In the 2014–15 season, Danault was recalled from the IceHogs by the Blackhawks and made his NHL debut on November 22, 2014, in a 7–1 victory over the Edmonton Oilers. Danault was initially assigned to the Rockford IceHogs to begin the 2015–16 season. On December 18, 2015, Danault was recalled from Rockford to the Blackhawks, and on December 20, he earned his first NHL point with an assist on Andrew Shaw's goal in a 4–3 win against the San Jose Sharks. He scored his first career NHL goal on January 8, 2016, the game-winner in a 3–1 win against the Buffalo Sabres. After solidifying a role amongst the Blackhawks' fourth line and contributing with 5 points in 30 games, on February 26, 2016, Danault was acquired by the Montreal Canadiens in exchange for forwards Dale Weise and Tomáš Fleischmann. On July 5, 2016, Danault re-signed with the Canadiens on a two-year contract. On January 13, 2018 during a game against the Boston Bruins, Danault was hit in the head by a shot from Zdeno Chára. Danault remained motionless on the ice for several minutes. He was eventually stretchered off the ice and taken to the hospital. The Canadiens lost the game 4–3 in a shootout. On July 15, 2018, Phillip re-signed with the Canadiens agreeing to a three-year contract. On 22 December 2018, Danault scored his first career NHL hat-trick in a 4–3 overtime victory against the Vegas Golden Knights. Danault finished the 2018–2019 season with a career-high 53 points, and finished seventh in votes for the Selke Trophy. Danault is a very sound Two-way forward, his game is often compared to Boston Bruins centerman Patrice Bergeron.
