Dallas Cowboys 2014 season Smith was signed as an
undrafted free agent by the
Dallas Cowboys after the
2014 NFL draft on May 11. Multiple injuries on the linebacker corps forced the team to sign him to the active roster for depth purposes on September 20. Smith made his NFL debut in the Cowboys' 34–31 season-opening win over the
St. Louis Rams. He was waived the following day and signed to the
practice squad. On October 4, he was promoted to the roster and released two days later. On October 18, he was promoted to the active roster and was later released on November 14. He remained on the roster after being added again on November 26, 2014. Smith finished his rookie season with ten game appearances.
2015 season training camp in 2015. On May 14, 2015, Smith was released after
rookie minicamp to make room for
free agent safety Danny McCray. He was re-signed on July 31, a day after
linebacker Keith Rivers announced his retirement. He made the team because of his
special teams ability and appeared in four games until being released on October 5, to make room for a suspended
Rolando McClain. On October 7, he was re-signed to the Cowboys' practice squad. On November 14, he was elevated to the active squad for depth purposes while linebacker
Sean Lee was out with a concussion. Smith played on November 15 against the
Tampa Bay Buccaneers. On November 16, he was waived to make room for linebacker
Mark Nzeocha. On November 18, he was re-signed to the practice squad. At the end of the 2015 season, at his exit meeting with head coach
Jason Garrett, Smith was told he was being converted into a fullback based on his work with the scout team, in order to give him a better chance to make the roster.
2016 season After the team chose not to re-sign
Tyler Clutts, he entered OTAs competing with
Rod Smith for the starting position. Although they both made the team, Keith was named the starting fullback at the end of training camp. Smith had his first career carry for a three-yard gain in the Cowboys' season-opening loss to the
New York Giants. The next game, he made his first career reception on a five-yard pass from quarterback
Dak Prescott during a 27–23 victory over the
Washington Redskins. On January 1, 2017, he earned his first career start during a 27–13 loss to the
Philadelphia Eagles. He contributed to rookie running back
Ezekiel Elliott winning the NFL rushing title, while finishing his first season as a fullback appearing in 16 games with one start. He was a core
special teams player.
2017 season Smith remained as the team's starting fullback, playing in 16 games, while blocking for Elliott and
Alfred Morris. He entered the 2018 offseason as a
restricted free agent, after the Cowboys gambled by not extending him a tender offer, looking to bring him back at a lower salary. The team ended up losing him and was forced to trade for fullback
Jamize Olawale.
Oakland Raiders On March 15, 2018, Smith signed a two-year contract with the
Oakland Raiders, reuniting with
special teams coach
Rich Bisaccia, who also had this role with the Cowboys. He appeared in all 16 games with three starts. In 2019, he suffered a knee injury that sidelined him for the majority of training camp. Due to this injury, rookie fullback
Alec Ingold became the Raiders' primary fullback in his place.. On August 31, 2019, Smith was released by the Raiders.
Atlanta Falcons On September 2, 2019, Smith was signed by the
Atlanta Falcons, to replace an injured
Ricky Ortiz. He appeared in all 16 games with five starts. On March 14, 2020, Smith signed a three-year contract extension with the Falcons. He was placed on the reserve/
COVID-19 list by the Falcons on July 29, 2020. He was activated on August 15, 2020. He appeared in all 16 games with seven starts in the 2020 season. In the 2021 season, he appeared in all 17 games with eight starts. In the 2022 season, he appeared in 17 games and started six. On March 13, 2023, Smith signed a one-year contract extension with the Falcons. Smith was fined $87,418 by the NFL after he knocked Detroit Lions running back
Zonovan Knight to the ground with his helmet while blocking. However, the play did not result in an in-game penalty. In a Week 5 win against the
Houston Texans, he caught a pass for 28 yards. ==Personal life==