Originally drafted as a safety, Bucannon transitioned to play a hybrid safety-linebacker role in the Cardinals's 3–4 defense.

He also caught 20 passes for 264 yards and a touchdown on offense, and led Vanden to the second round of the CIF Sac-Joaquin Section Division III playoffs.

On September 8, 2014, he earned his first career start in the season opener against the San Diego Chargers and finished his first game with five tackles.

In a 24–20 win over the Philadelphia Eagles on October 26, he recorded a season-high eight total tackles and a pass deflection.

On November 9, 2014, Bucannon, racked up five total tackles (four solo) and his first career sack in a 31–14 victory over the St. Louis Rams.

After finishing the season 11–5, the Cardinals played the Carolina Panthers in a Wild-card game on January 3, 2015.

In a Week 10 game against the Seattle Seahawks, he earned his first sack of the season while also recording seven total tackles in a 39–32 victory.

Bucannon started 13 games in 2016, recording 91 tackles and four passes defensed before being placed on injured reserve on December 13, 2016 with an ankle injury.

[17] In 2018, Bucannon played in 13 games with six starts, recording a career-low 38 tackles, one sack, and a forced fumble.

[21] On September 8, 2020, Bucannon was released and due to new COVID-19 roster management rules, was re-signed to the practice squad the next day.