After a short time in Boston, Smith joined the Florida Panthers for two seasons before landing with the Vegas Golden Knights.

[7] Following the draft, Smith began his freshman season with the Redhawks in the Central Collegiate Hockey Association (CCHA) while majoring in sport studies.

[13] On March 25, 2012, Smith relinquished his final year at Miami to sign a three-year, entry-level contract with the Dallas Stars.

[18] He was promoted to Dallas for the season once play resumed in January 2013 and scored his first career NHL goal on February 15, 2013, against Cory Schneider of the Vancouver Canucks.

[19] As a result of his early success, Smith was promoted to a top six position in February and played left wing on a line with Derek Roy and Loui Eriksson.

[1] On July 1, 2015, Smith was traded by the Bruins, along with Marc Savard's contract, to the Florida Panthers in exchange for Jimmy Hayes.

[29] On June 21, 2017, Smith was traded at the 2017 NHL Expansion Draft to the Vegas Golden Knights due to salary cap issues.

Both he and teammate Jonathan Marchessault were acquired by the Golden Knights, with the Panthers receiving a fourth-round pick in the 2018 NHL Entry Draft.

[34] Upon returning to the Knights, Smith remained with Marchessault and Karlsson and recorded his 100th career NHL goal in a 4–2 win over the Pittsburgh Penguins on October 11, 2018.

[36] As the Knights qualified for the Stanley Cup playoffs for the second consecutive year, Smith recorded one goal and five assists in their series against the San Jose Sharks.

[34] At the time of the pausing of the 2019–20 season due to the COVID-19 pandemic, Smith had scored a career high 27 goals in 71 games played.

After surpassing the Chicago Blackhawks in the first round of the 2020 Stanley Cup playoffs, Smith tied with Mark Stone for team lead in points.

[41] By the 2022–23 season, Smith was one of six remaining original members of the Golden Knights, alongside Marchessault, Karlsson, Brayden McNabb, Shea Theodore and William Carrier.

[42] On June 28, 2023, Smith was traded by the Golden Knights to the Pittsburgh Penguins in exchange for a third round pick in the 2024 NHL Entry Draft.