The deadly crash had caused all mainlanes westbound on the North Loop at TC Jester to close but the lanes have since then been reopened, police added.
Police said they received a call at about 2:10 p.m. regarding a man walking on the freeway ramp. They said the man stepped in front of the 18-wheeler and was struck.
The man was rushed to Memorial Hermann Greater Heights Hospital where he was pronounced dead.
SkyEye captured footage in the video player above from the scene which showed a massive backup at the time.
Video also captured a number of skid marks the big rig made on the freeway from what seemed like an attempt to avoid hitting the man.