He was also part of St. Thomas Academy's Class A high school hockey tournament, winning the championship in 2006 and playing again in 2007.

Although private-to-public school transfers were rare, the daily 20-mile round trip commute to St. Thomas and a desire to play with teammates he grew up with factored into his decision.

In the fall, he won the starting quarterback position and passed for 2,049 yards and 14 touchdowns for the Edina Hornets, who finished with a 10–1 record after losing to the eventual state champion Eden Prairie in the Section 6AAAAA championship game.

[9] Playing in the pre-season Upper Midwest Elite League, Lee scored 12 goals with 17 assists in 18 games for Team Southwest.

[11] He spent the upcoming season playing for the Green Bay Gamblers in the United States Hockey League (USHL) and was their leading scorer.

Lee concluded his collegiate career on April 1, 2013, by signing a two-year, entry-level contract with the New York Islanders.

[13] He appeared in one more game for the Islanders that season, where he tallied his first NHL assist on the game-winning goal in a 4–2 win over the Tampa Bay Lightning.

[15] Lee participated in his first Islanders training camp ahead of the 2013–14 season but was reassigned to their American Hockey League (AHL) affiliate, the Bridgeport Sound Tigers, on September 30, 2013.

[16] He immediately made an impact in the AHL, leading the team in scoring with 22 goals and 19 assists for 41 points through the first half of the season.

[17] As he continued to show his offensive output at the NHL level, Lee began to earn recognition as a possible linemate for John Tavares and Kyle Okposo.

Head coach Jack Capuano said it was a tough decision to demote Lee because of his impressive showing at training camp but it was the result of a "numbers game.

[21] As the season progressed, Lee became a mainstay in the Islanders lineup while playing alongside Ryan Strome and Brock Nelson.

[23] After Okposo was declared out for six to eight weeks in late January, Lee replaced him on the Islander's top line with Tavares and Josh Bailey.

[29] The line remained together until the end of December when Lee returned to Tavares' wing in an effort to spark an increase in both of their offensive output.

[31] He continued to steadily improve his scoring as the season progressed before suffering a broken fibula during a game against the New York Rangers on April 7.

[33] After sitting out the entirety of the Islanders' playoff berth, Lee returned to the team's training camp in September healthy and eligible to play.

[35] In spite of the slow start, Lee experienced a career year while playing mostly on a line with team captain John Tavares and Josh Bailey.

[37] At the beginning of the 2018–19 season, after the departure of John Tavares to the Toronto Maple Leafs, Lee was named the 15th captain of the Islanders.

[39] On March 17, 2021, the Islanders announced Lee would miss the remainder of the 2020–21 season to have surgery on a torn ACL sustained after a massive hit with New Jersey Devils forward Pavel Zacha six days earlier.