Humphrey was stellar in 2018, hauling in 86 catches for 1,176 yards and nine touchdowns.
"It has not been an easy decision, but after a lot of thoughts and prayers, I have decided to forgo my senior season and enter the 2019 NFL Draft," Humphrey said in a statement. "I'm forever grateful to be a part of a family that was so close together."
The 6-foot-4, 222-pound Humphrey is ranked ninth among draft-eligible receivers, according to ESPN draft expert Mel Kiper. His 86 catches were fifth most in school history and his 1,176 yards were third most.
He was part of a dynamic receiver duo for the Longhorns with Collin Johnson, who announced last week that he would return for his senior season. Texas defeated Georgia in the Allstate Sugar Bowl on Jan. 1 to register its first 10-win season since 2009.