Police were called to Dewsbury Road, Beeston, shortly before 2am today (Saturday).
They had received reports of an ongoing fight outside Broadway Hotel.
A man was seriously injured after being assaulted.
He was taken to hospital for urgent treatment.
Police have cordoned off the car park of Broadway Hotel as they investigate the attack.
Anyone with information is asked to contact Leeds CID via the LiveChat or by calling 101, quoting crime reference 13220415128.