Francis "Fraggle" Green, 30, and Robert Daniel, 22, assaulted Susanne Simpson, 43, outside the Cairn bar in Balornock, Glasgow, on October 23, 2011.
A trial at Glasgow Sheriff Court found the men guilty of assaulting Miss Simpson to her severe injury.
Sheriff Bill Totten told them: "You have been convicted by the jury in this case of a brutal attack on a defenceless female that resulted in her severe injury and at the time of the incident you were on bail."
He added it had been properly recognised that there was no alternative to a custodial sentence.
Daniel was jailed for three years and Green sentenced to three and a half years.