[1] He grew from a 6-2, 250-pound offensive lineman as a junior to a 6-4, 300-pound senior, leading Comanches to an 11–2 record and league title, earning All-Southern Seven Conference and All-Class 5A selection.

Armstead enrolled in the University of Arkansas at Pine Bluff, where he played for the UAPB Golden Lions football team from 2009 to 2012.

[11] The selection was announced by retired Saint Steve Gleason, at the time using a wheelchair and a computerized voice due to his advanced ALS.

On September 22, he played in his first NFL career regular season game in a Week 3 win against the Arizona Cardinals.

He made his first NFL career postseason start in a Wild Card win against the Philadelphia Eagles.

Armstead started the first 14 regular season games, despite a concussion in a Week 4 loss to the Dallas Cowboys,[14] but missed the last two due to injury.

[23] After starting the first two games of the 2016 season, Armstead was unable to play for Weeks 3 and 4 after suffering a knee injury.

[24] On June 14, 2017, during minicamp, Armstead suffered a torn labrum which required surgery, which was expected to make him miss 4–6 months.

[29] On November 27, he was diagnosed with a Grade 2 pectoral strain (partial tear) and ruled out approximately 2–3 weeks.