NCAA On April 18, 2014, Frederic committed to play
college ice hockey for the
Wisconsin Badgers beginning in the
2016–17 season. The summer before joining the Badgers, Frederic, who had previously been recruited by the
Boston University Terriers, was selected by the
Boston Bruins in the first round, 29th overall, of the
2016 NHL entry draft. Despite being drafted, Frederic committed to Wisconsin, and he scored his first collegiate goal on October 8, 2016, as part of a 6–5 defeat of the
Northern Michigan Wildcats. With six points in his first four games, including a four-point game against the
Boston College Eagles, Frederic was named the
Big Ten Conference's Second Star of the Week for the week ending October 18. After breaking his hand in practice on November 17, the Badgers' goals per game dropped from 3.75 in the eight games he had played to 2.67 in the six games he missed. Centering a line with
Cameron Hughes and
Luke Kunin, Frederic was second to Kunin with 15 goals and 33 points in 30 regular season games. Although the Badgers lost the Big Ten tournament to
Penn State in double overtime, thus keeping them out of the
NCAA tournament, Frederic was named the
Big Ten Men's Ice Hockey Freshman of the Year, as well as the recipient of the Spike Carlson–Chris Chelios Award for the Badgers'
most valuable player (MVP). He was also named to both the All-Big Ten Second Team and Freshman Team. When Hughes was promoted to Badgers
captain shortly before the
2017–18 season, Frederic became one of four alternate captains. He struggled in the first half of the regular season, dropping from 1.1 points per game during his freshman year to 0.76 as a sophomore, in part because his opponents were targeting him. In an effort to remedy this, coach
Tony Granato dropped Frederic from the first to the third offensive line, where he centered Matthew Freytag and Sean Dhooghe. On February 7, after back-to-back three-point outings against the
Michigan Wolverines, Frederic was named the Big Ten second star of the week. Although Frederic delivered two goals in the Big Ten tournament game, the Badgers lost to Michigan 7–4 and were kept once again from the NCAA tournament. Frederic had 17 goals and 32 points in 36 regular season games for the Badgers that year and was named an All-Big Ten honorable mention, but had two four-game scoring droughts as Wisconsin finished the season 14–19–4. After the 2017–18 season ended, Frederic signed a three-year,
entry-level contract with the Bruins, ending his college hockey career.
Professional Boston Bruins (2018–2025) Frederic's contract with the Bruins started during the
2018–19 season, but he was able to finish out the
2017–18 season with the
Providence Bruins, Boston's
American Hockey League (AHL) affiliate, on an
amateur tryout contract. The off-deason departure of
Riley Nash to the
Columbus Blue Jackets left the Bruins' third-line center position open for the
2018–19 season, and Frederic entered training camp in contention with
Jack Studnicka and
Jakob Forsbacka Karlsson for the role. Veterans David Backes and
Sean Kuraly were ultimately awarded the job, while Frederic and his competitors were sent back to Providence. Ultimately, however, the third-line center became a rotating position, and Frederic was called up from Providence on January 29 to try out the role. He made his NHL debut that night, skating alongside his childhood hero Backes, and received a five-minute
major penalty for
fighting with
Winnipeg Jets forward
Brandon Tanev. After 11 scoreless games for Boston, Frederic was sent back down to Providence on February 22, shortly before the
trading deadline, in order to clear
salary cap space for new acquisition
Charlie Coyle. Ultimately, Frederic played in 15 NHL games during the 2018–19 season, with no goals or assists in any of them, but had 14 goals and 25 points in 55 games with Providence. Although he began the
2019–20 season in Providence, injuries soon decimated the Bruins' offensive core, and Frederic was called up to Boston on November 14 to replace an injured
Zach Senyshyn. He skated on the third line with
Par Lindholm and
Danton Heinen, playing on the
left wing instead of his usual center. His call-up was short-lived, as Frederic,
Paul Carey, and
Urho Vaakanainen were all sent down to Providence on November 18 to make room for
Jake DeBrusk,
Patrice Bergeron, and
Brett Ritchie, all of whom were returning from their respective injuries. Although he played in only two NHL games that season, Frederic made a much larger impact in the AHL, where he scored eight goals and 32 points in 59 regular season games, all while leading the league with 148
penalty minutes. By the time that the AHL season was canceled in March due to the
COVID-19 pandemic, the Providence Bruins were on a 12-game winning streak and were poised to take the No. 1 seed in the Eastern Conference. When the NHL returned to play for the
2020 Stanley Cup playoffs, Frederic was one of 31 players selected to join the team in the Toronto "
bubble". He contracted the
COVID-19 virus during the pre-playoff training camp, however, and could not play with the team during their postseason run. Frederic opened the
2020–21 season as a member of the Bruins'
taxi squad, ready to fill in for either
Craig Smith or
Brad Marchand as needed. After cementing his place on the Bruins lineup by way of fighting with
P. K. Subban of the
New Jersey Devils early in the season, Frederic finally picked up his first NHL point on January 23, an assist on Coyle's goal in a 3–1 defeat of the
Philadelphia Flyers. His first NHL goal also came against the Flyers, a second-period shot past
Carter Hart during the
NHL Outdoors at Lake Tahoe game on February 21. What was poised to be a strong rookie season for Frederic was suddenly derailed after April 6, when he contracted a mysterious, non-COVID-19 illness. Frederic suffered a
fever of over that sidelined him for some time, and when the Bruins acquired
Curtis Lazar and
Taylor Hall in a late-season trade with the
Buffalo Sabres, it was difficult for Frederic to find his way back into the lineup. After contracting the illness, he made only six more regular season appearances for Boston. He scored four goals and one assist in 42 regular season games, but did not make an appearance in any of the Bruins' 11 games at the
2021 Stanley Cup playoffs, even when the fourth line wavered and Boston eventually fell to the
New York Islanders. An impending
restricted free agent after the 2020–21 season, Frederic signed a two-year, $2.1 million contract extension with the Bruins on June 25, 2021. Shortly thereafter, he was one of the seven
forwards that the Bruins chose to protect in the
2021 NHL expansion draft. He began the
2021–22 season on an inexperienced fourth line with
Tomáš Nosek and
Karson Kuhlman, where he was expected to maintain possession of the puck against opposing defense. On November 9, Frederic left the Bruins' game against the
Ottawa Senators after taking a hit from
Josh Brown. He missed two weeks with a concussion, and upon his return to the lineup on November 28, Frederic was promoted to a third line with
Nick Foligno and Kuhlman. In December, Frederic was one of nine Bruins players to enter COVID-19 protocols before the NHL ordered an eight-day team shutdown. Frederic suffered another upper-body injury after the break, this time in Boston's January 10 game against the
Washington Capitals. He returned to the lineup on February 8, after the
NHL All-Star Game break. In the second half of the season, Frederic took a less physical approach to avoid taking penalties, and he found chemistry on a line with center
Charlie Coyle. Playing in 60 regular season games as a bottom-six center and left wing, Frederic recorded eight goals and 18 points, and outgoing head coach
Bruce Cassidy criticized his discipline and offensive initiative. The Bruins faced the
Carolina Hurricanes in the first round of the
2022 Stanley Cup playoffs. Frederic struggled in the postseason: he missed three games after taking a penalty in Game 2, and in Game 7, a defensive miscue on his part allowed
Max Domi of the Hurricanes to score, ultimately ending the Bruins' season. Leading into the
2022–23 season, Frederic practiced shooting and skating at his family home, and he met with a mental toughness coach. After a poor preseason in which Frederic believed he was too concerned with making mistakes, incoming coach
Jim Montgomery told him to "hunt and hit". This simplified approach helped Frederic's confidence and gave him "a better sense of" when to initiate fights. A natural center, his confidence and performance also improved with a move to right wing, with Coyle centering a line that also included
Taylor Hall. By the end of December, the Bruins coaching staff used Frederic in all three offensive roles depending on roster injuries, but Montgomery viewed him as most creative on the right wing. Playing in 79 games, mostly with Hall and Coyle, Frederic finished the regular season with a career-high 17 goals and 31 points. That momentum failed to carry over into the
2023 Stanley Cup playoffs, in which the Bruins lost a seven-game first-round series to the
Florida Panthers. Frederic was scratched for two games in favor of rookie
Jakub Lauko, and he was held off the board in the five games he did play. A restricted free agent after the 2022–23 season, Frederic signed a two-year, $4.6 million contract extension with the Bruins on August 1, 2023. As the season progressed, Frederic's speed developed, which allowed him to take a more dynamic role on offense. On January 6, Frederic, filling in for an injured
James van Riemsdyk, scored the first power play goal of his professional career against the
Tampa Bay Lightning. Appearing in all but one regular season game for Boston, Frederic set career highs with 18 goals and 40 points, and he received the NESN 7th Player Award as the Bruin who exceeded fan expectations that season. Frederic attributed his growth over the past two seasons to Montgomery, who "[gave] me confidence and let me play and learn from some of my mistakes".
Edmonton Oilers (2025–present) On March 4, 2025, Frederic was traded to the
Edmonton Oilers alongside
Max Jones and unsigned prospect
Petr Hauser in a three-team deal, which saw the Bruins receive
Max Wanner, a second-round draft pick, and a fourth-round pick, while the
New Jersey Devils received prospect
Shane Lachance for retaining half of Frederic's salary. Frederic played his first game for the Oilers on April 5, 2025, against the
Los Angeles Kings in a 3–0 losing effort. Frederic scored his first goal as an Oiler on May 1, 2025, in Game 6 of the Oilers first round matchup against the Kings. It would turn out to be the series winning goal, as the Oilers won 6–4 and advanced to the second round. On June 27, 2025, Frederic signed an eight-year, $30.8 million contract extension with the Oilers. ==International play==