Along with Max and Griffin, he is one of three hockey-playing brothers, and are the sons of former National Hockey League (NHL) All-Star Paul Reinhart.

[20] Reinhart also participated in the 2011 Canada Winter Games midway through the 2010–11 season, winning gold with the British Columbia U16 team.

[25] Reinhart suited up for seven WHL playoffs games, registering zero points in the process, as part of the Ice's Ed Chynoweth Cup championship team.

Due to his excellent play in his first full season, Reinhart was awarded the Jim Piggott Memorial Trophy as the top rookie in the WHL.

[39] After being selected second overall by the Buffalo Sabres in the 2014 NHL Entry Draft, Reinhart signed a three-year entry-level contract with the team.

[41] He made his NHL debut on October 9, 2014, against the Columbus Blue Jackets, becoming the sixth-youngest player to dress for the Sabres in franchise history.

[42] Reinhart recorded his first NHL point, an assist on a goal by Nicolas Deslauriers, on October 25 against the San Jose Sharks.

[48] To ease his transition into professional hockey, Americans head coach Chadd Cassidy used him primarily on right wing instead of his natural position of center.

[52][53] Following the Sabres' training and development camps, Reinhart was named to their opening night roster for the second consecutive season.

[60] At the start of February, Reinhart missed three games with a concussion but scored the Sabres' lone goal in his return as they fell to the Boston Bruins.

[61] In the final 18 games of the season, Reinhart left O'Rielly's line and joined Eichel as the Sabres' top unit.

[62] After recording a goal and an assist in a win over the Ottawa Senators on March 18, he and Jack Eichel became the first pair of Sabres rookies with 20-goal seasons since 1975.

[66] After Eichel suffered a lower body injury during the preseason, Reinhart began the 2016–17 season on the wing of Ryan O'Reilly and Kyle Okposo.

[67] During his first month in this position, Reinhart experienced a seven-game pointless drought that was snapped with two assists in a game against the Calgary Flames on November 21.

[68] However, he continued to experiences bouts of pointlessness and was eventually transitioned back to right wing on a line with O'Rielly and William Carrier.

[69] When O'Rielly missed time in December due to an appendectomy, Reinhart was transitioned back to a centre position temporarily.

[73] Reinhart finished the season with a new-career high 47 points as the Sabres again failed to qualify for the Stanley Cup playoffs.

[76] This reunion was shortlived as head coach Phil Housley continued to shuffle the forward lines in an effort to create more offense.

[77] As Reinhart continued to struggle offensively through the first half of the season, scoring only 11 points in 34 games, Housley tried him back on Eichel's wing again in late December.

[81] On July 24, 2021, Reinhart was traded by the Sabres to the Florida Panthers in exchange for Devon Levi and a 2022 first-round pick.

[85] Reinhart then captained the under-18 team at the 2012 Ivan Hlinka Memorial Tournament as Canada won its fifth consecutive gold medal in the event.

[87] Reinhart scored three goals and four assists to help Canada win the gold, ending the United States' record of four consecutive championships.

Reinhart represented Team Canada at the 2016 IIHF World Championship helping win Gold and finishing the tournament with four assists in 10 games.

On April 29, 2019, Reinhart was named to the Team Canada roster for the 2019 IIHF World Championship held in Slovakia.

[94] Reinhart helped Canada progress through to the playoff rounds before losing the final to Finland to finish with the Silver Medal on May 26, 2019.