Frederic briefly attended De Smet Jesuit High School where he played football and hockey before playing two seasons for the U.S. National Team Development Program.[2][3] Despite being drafted in the first round of the 2016 NHL Entry Draft Frederic agreed to play hockey for the University of Wisconsin. During his freshman season with the Badgers, Frederic was named to the All-Big Ten second-team and the Big Ten All-Freshman team after finishing fourth among all freshman in points-per-game and garnering the second-highest point total on the team.[3] Frederic was also named the Big Ten Freshman of the Year becoming the first Wisconsin player to earn the title since Dany Heatley in 1999–2000.[4]

​

Frederic was named an alternate captain in his sophomore year, and in the 2017–18 season, he led the Badgers with 17 goals, 15 assists and 32 points in 36 games.

​

On March 13, 2018, Frederic opted to conclude his collegiate career, signing a three-year entry-level contract with the Boston Bruins of the National Hockey League (NHL) starting in the 2018–19 season.[4][5] He joined AHL affiliate, the Providence Bruins, on an amateur try-out deal for the remainder of the season.[4] Frederic's first-ever callup to Boston's NHL team occurred on January 28, 2019, wearing number 82. He got into his first NHL fight during the second period of his debut game, taking on Brandon Tanev with his parents in attendance. [6]

​

On February 21, 2021, Frederic scored his first NHL goal in a 7–3 win against the Philadelphia Flyers during the NHL Outdoors at Lake Tahoe event, also becoming the third player to score its first goal in an outdoor NHL game.[7]

​