Police were called at around 4:30am to Club Railway to reports of multiple people suffering stab wounds following an incident at the nightclub.
Six men went to hospital for treatment to knife wound injuries but a spokesperson added that none of the injuries are thought to be life-threatening.
Police have also arrested seven people in connection with the incident.
Det Insp Ria Holmes, of Bradford CID, said: “I would like to appeal to members of the public who were in the nightclub itself yesterday evening, into the early hours or in the vicinity and witnessed anything in connection with this incident.
“I would urge anyone with any information to come forward and speak to the police to assist with our enquiries.”
Anyone with any information is asked to contact Bradford CID via 101 quoting crime reference number 13180154054 or alternatively information can be given to Crimestoppers anonymously on 0800 555 111.