The victim was approached by a man at about 8.10pm on Friday, while she was walking along Park Avenue near Greenhead College.
He asked her for directions to New Kirklees College.
While the victim, 23, was trying to direct the offender he sexually assaulted her, a West Yorkshire Police spokesperson said.
He then walked away from the scene.
The offender has been described as an Asian man, 6ft tall, in his late 20s or early 30s.
He was of slim build and had black hair.
Anyone with information is asked to contact police on 101, quoting crime reference 13170586310.