Before his senior season, Rankin was projected as a first round pick in the 2018 NFL Draft by several writers. Rankin's draft stock began to slide after he sustained an ankle injury during the season and also had mediocre performances against LSU and Auburn. On November 16, 2017, it was announced that Rankin had accepted his invitation to play in the 2018 Senior Bowl. On January 20, 2018, it was reported that Rankin would be unable to play in the Senior Bowl due to an ankle injury he sustained in the TaxSlayer Bowl. Rankin attended the NFL Scouting Combine in Indianapolis, but did not perform any drills due to the foot injury he sustained. On March 28, 2018, he attended Mississippi State's pro day, but chose to only perform the broad jump and vertical jump. Rankin also attended a private meetings with representatives from the Cincinnati Bengals and Denver Broncos. At the conclusion of the pre-draft process, Rankin was projected to be a second or third round pick by NFL draft experts and scouts. He was ranked as the fourth best offensive tackle by Scouts Inc. and was ranked the seventh best offensive tackle in the draft by DraftScout.com and Sports Illustrated.
Houston Texans
The Houston Texas selected Rankins in the third round of the 2018 NFL Draft. Rankins was the eighth offensive tackle drafted in 2018. The pick used to draft Rankin was acquired in a trade that sent Duane Brown to the Seattle Seahawks. On May 10, 2018, the Houston Texans signed Rankin to a four-year, $3.54 million contract that includes a signing bonus of $901,268. The Texans stated they drafted Rankin to play offensive tackle although many scouts and draft experts viewed him as an interior offensive lineman in the NFL. During rookie minicamp, Rankin sustained a foot injury which required surgery and was sidelined for the entire training camp.
Kansas City Chiefs
On August 31, 2019, Rankin was traded to the Kansas City Chiefs in exchange for running backCarlos Hyde. He started five games at left guard before suffering a knee injury in Week 10. He was placed on injured reserve on November 11, 2019. During his absence, the Chiefs went on to win Super Bowl LIV, their first championship in 50 years. He was placed on the active/physically unable to perform list at the start of training camp on July 31, 2020.