Maine Red Claws (2016–2017) After going undrafted in the
2016 NBA draft, Lee joined the
Miami Heat for the
2016 NBA Summer League. On September 26, 2016, he signed with the
Boston Celtics. He was later waived by the Celtics on October 20 after appearing in two preseason games. On October 31, he was acquired by the
Maine Red Claws of the
NBA Development League as an affiliate player of the Celtics. On January 10, 2017, he was waived by the Red Claws after suffering a season-ending injury. In 16 games, he averaged 17.8 points, 6.3 rebounds, 3.4 assists and 1.1 steals in 34 minutes.
Santa Cruz Warriors (2017–2018) On August 24, 2017, Lee was traded to the
Santa Cruz Warriors of the
NBA G League.
Atlanta Hawks (2018) On March 13, 2018, Lee signed a 10-day contract with the
Atlanta Hawks. On March 23, the Atlanta Hawks signed Lee to a second 10-day contract. On April 2, the Atlanta Hawks signed Lee for the remainder of the season.
Golden State Warriors (2018–2022) On July 14, 2018, Lee signed a
two-way contract with the
Golden State Warriors, which would lead him to return to the
Santa Cruz Warriors. On July 31, 2019, the
Golden State Warriors re-signed with Lee on another two-way contract. On October 28, Lee recorded a double-double with a career-high 23 points, 11 rebounds and two assists in a 134–123 road victory over the
New Orleans Pelicans. On December 25, Lee got his second double-double of the season with 22 points and a career-high 15 rebounds in a 116–104 win against the
Houston Rockets. Lee picked up ample playing time due to a litany of injuries that befell the Warriors' roster (including a hand fracture in November that cost Lee 14 games) and burned through the 45-day allotment with the NBA team on his two-way contract. On January 15, 2020, the Golden State Warriors signed Lee to a multi-year contract. On December 27, 2020, Lee put up 12 points, alongside a game-winning three-pointer, in a 129–128 win over the
Chicago Bulls. On June 16, 2022, Lee won the
2022 NBA Finals with the Warriors.
Phoenix Suns (2022–2025) On July 7, 2022, Lee signed with the
Phoenix Suns. On October 19, Lee made his Suns debut, putting up 11 points, two rebounds, two assists, and an off-balance, game-winning baseline jumper in a 107–105 win over the
Dallas Mavericks. On January 13, 2023, Lee scored a career-high 31 points off the bench in a close 121–116 loss to the
Minnesota Timberwolves. During training camp the following season, Lee injured his right meniscus resulting in surgery. The
meniscus tear would later result in him missing the rest of that season in the process. Lee would later reveal that the meniscus tear turned out to be a rare double root tear that required an extended recovery period for him, which caused him to suffer from depression to the point of needing to seek therapy at the time. On July 6, 2024, Lee re-signed with the Suns. He made 25 appearances off of the bench for Phoenix in the
2024–25 NBA season, averaging 3.3 points, 0.8 rebounds, and 0.4 assists.
Ironi Ness Ziona (2025) On August 23, 2025, Lee signed with the Israeli team
Ironi Ness Ziona for the 2025–26 season. He played in three games for the team, averaging 7.0 points in 22.7 minutes, and shooting 29.2% from the field. On December 28, it was reported that Lee was parting ways with the team. ==National team career==