A redshirt freshman in 2017, Hemphill-Mapps emerged as a key receiver for the Longhorns and finished with 37 receptions, tied for second on the team behind Collin Johnson.
"Disappointing, but we wish Reggie the best," Herman said during his signing day news conference. "We hope he finds what he's looking for out there, but next man up."
Along with Johnson, the Longhorns will still return key playmakers Lil'Jordan Humphrey and Jerrod Heard to their receiving rotation. Texas also signed three ESPN 300 receivers to its class: Al'vonte Woodard, Brennan Eagles and Joshua Moore, whom the Longhorns flipped from Nebraska before signing him Wednesday.