The 5'9", 180 lb. prospect said in July that the Cougars and Utah were his two leaders, but a recent unofficial visit to Pullman sealed the decision for Morrow.
"I talked with my family about it and after I took my unofficial, I just knew it was the place to be," he said on Monday of why he decided to pull the trigger.
"It's just a great place," he reiterated.
Morrow and the Patriots have started out the season 3-0, and the running back already has five touchdowns.
As a junior, the talented back rushed for 1,777 yards.
Morrow is the twelfth 2013 commit to give his verbal to Washington State.