It happened on Sunday 4th March at the junction of Kirkgate and Cross Church Street.
The male victim, who is in his 20s, was approached by two males at the junction in Huddersfield town centre.
One of the suspects produced a large knife and slashed the victim’s face causing him serious injuries.
He was later treated in hospital and had stitches to his face.
The suspects left the scene towards John Williams Street.
One of the suspects is described as an Asian male wearing a hoody and the other was described as a white male wearing a green hooded jacket.
DS Alex Bacon, of Kirklees CID, said: “This was a violent attack on the street at the weekend when people were out enjoying the night time economy in the town centre.
“This is a busy street and I would like to appeal to members of the public who may have been out and in the vicinity and either witnessed the incident or have any information to come forward and speak to the police to assist with our enquiries.”