The victim, who is in his 20s, was attacked at around 4:20am last Sunday at the junction of Kirkgate and Cross Church Street.
Two men approached him at the junction, one taking out a large knife and slashing his face, causing serious injuries.
He was later treated in hospital and had stitches.
The suspects made off towards John Williams Street.
One was described as an Asian male wearing a hoody and the other 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.”
Call Kirklees CID via 101 or Crimestoppers anonymously on 0800 555 111.