[4] As a junior, he started at linebacker, collecting 110 tackles, 5 sacks and 3 fumble recoveries, while receiving All-CIF Southeast Southern Section honors.

As a senior, he tallied 132 tackles (90 solo), receiving 2009 Miramonte League Defensive Player of the Year and All-California Interscholastic Federation Southeast Southern Section honors.

[2] In 49 games, Smith made 45 starts and had 476 total tackles, the second most among all-time San Jose State players.

Smith earned Academic All-Western Athletic Conference (WAC), Football Writers Association of America Freshman All-America, second-team All-WAC, and San Jose State Scholar-Athlete honors this season.

[13][14][15] Multiple injuries on the linebacker corps forced the team to sign him to the active roster for depth purposes on September 20.

[23] On May 14, 2015, Smith was released after rookie minicamp to make room for free agent safety Danny McCray.

[27] On November 14, he was elevated to the active squad for depth purposes while linebacker Sean Lee was out with a concussion.

[citation needed] 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.

[30] After the team chose not to re-sign Tyler Clutts, he entered OTAs competing with Rod Smith for the starting position.

[31] 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.

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.

[32][33] Smith remained as the team's starting fullback, playing in 16 games, while blocking for Elliott and Alfred Morris.

[34][35] 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.

[37] 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.

[50] 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.