Quade Jay, 25, admitted assaulting a 27-year-old man outside The Vaults, in Castle Gates.
The pub was closed at the time and no one involved in the incident had been in the premises, although the police said the attack happened outside.
The victim was taken to Royal Shrewsbury Hospital for treatment after he sustained a number of injuries. The incident happened at around 11pm on June 29 this year.
Jay, of no fixed abode, will be sentenced on Thursday this week at Shrewsbury Crown Court.
Jay, who appeared from HMP Hewell via video link, remains in custody.