The Vegas Golden Knights knew what they were doing when they acquired Smith in a trade at the 2017 NHL Expansion Draft.

Smith was a big reason the Florida Panthers, coached by Gerard Gallant, won the Atlantic Division title in 2015-16. Two seasons later, he played a key role in helping the Vegas Golden Knights to the best finish by a first-year team in NHL history -- again on a team coached by Gallant. Smith, a right wing and the brother of New York Rangers defenseman Brendan Smith, teamed with center William Karlsson and left wing Jonathan Marchessault to form one of the most effective lines in the NHL. That line was broken up when the Golden Knights traded Smith to the Pittsburgh Penguins on June 28, 2023, for a third-round pick in the 2024 NHL Draft.

Smith was traded to the Rangers by the Penguins on July 1, 2024, for a conditional fifth-round pick in the 2025 NHL Draft and a second-round pick in the 2027 NHL Draft. He returned to Vegas on March 6, 2025, when he was acquired for Brendan Brisson and a 3rd-round pick in the 2025 NHL Draft, and signed a one-year, $2 million contract to stay with the Golden Knights on July 1, 2025.

In 2017-18, Smith had what was NHL career highs in assists (38) and points (60), helping Vegas win the Pacific Division, then was even better in the Stanley Cup Playoffs. The Golden Knights became the first expansion team since the St. Louis Blues in 1968 to advance to the Cup Final, and Smith led them in scoring with 22 points (five goals, 17 assists).

Smith showed his 2017-18 season was no fluke during the next two seasons, finishing with 19 goals and 53 points in 2018-19 and scoring an NHL career-high 27 goals in 2019-20.

Smith reached the pinnacle of his NHL career when the Golden Knights defeated the Florida Panthers 9-3 in Game 5 of the 2023 Stanley Cup Final to win the NHL championship for the first time in their history. He became the first player since 2017 (Patric Hornqvist for the Penguins against the Nashville Predators in the 2017 Final) to score a Cup-clinching goal against his former team and he was the first to receive the Cup from Vegas captain Mark Stone.

A third-round pick (No. 69) by the Dallas Stars in the 2009 NHL Draft, the 6-foot, 185-pound forward is a strong, agile skater with a quick shot. At age 16, Smith scored 80 goals in 70 games for the Toronto Nationals of the Greater Toronto Hockey League.

After playing two seasons for St. Michael's of the Ontario Junior Hockey League, Smith continued his development at Miami University, where he scored 66 goals and finished with 122 points in 121 games. He scored 30 goals and had 48 points as a junior in 2011-12, when he was named a finalist for the Hobey Baker Award, given to the top player in NCAA Division I hockey.

Smith opted to turn pro and signed with the Stars on March 25, 2012. He was scoreless in three games, but made the Stars for good in January 2013 and scored his first NHL goal against the Vancouver Canucks on Feb. 13, 2013.

On July 4, 2013, he was traded to the Boston Bruins. He had a breakout season in 2013-14, finishing with 51 points (20 goals, 31 assists). But on July 2, 2015, Smith was traded to the Panthers. He scored 25 goals and finished with 50 points in 2015-16 to help Florida win the division title, then had eight points (four goals, four assists) in six Stanley Cup Playoff games.

On July 3, 2016, Smith signed a five-year contract with the Panthers, but less than a year later, Vegas acquired him in a trade at the expansion draft.