Johnson's mother, Linda Hanks, says Texas Aamp;M University police told her Thursday the 18-year-old is unharmed.
University police said they traveled to Dallas to look for Johnson on Wednesday. Johnson was found safe about 2:30 a.m. Thursday with the help of the Dallas police and the Texas Rangers.
Police said Wednesday that Johnson was last seen leaving his College Station residence around 5 p.m. Monday.
Hanks told WFAA-TV she traveled from Dallas to College Station while authorities searched for her son. He turned up 180 miles away in Dallas.
Hanks says Johnson didn't contact her and that she has no other information. Campus police said that they are not releasing further details.
Coach Kevin Sumlin says he's relieved Johnson has been found and is concerned for Johnson's health and well-being.
Johnson played in 10 games this season, with 30 catches for 339 yards and a touchdown.