Mold Crown Court heard that victim Megan Williams had a permanent scar above her eyebrow.
Serena Yapp, 23, of Oakland Park, Newtown, admitted assault causing grievous bodily harm.
Yapp had a 16-month suspended jail term was imposed with 200 hours unpaid work and she must pay £2,400 compensation.
A two-year restraining order was also made.
Judge Nicola Saffman excluded Yapp from pubs and nightclubs for 18 months as part of her punishment.
Miss Williams said she believed she was attacked “for no reason” at the Newtown's Steam Mill nightspot last October. She suffered dizziness and went to the Royal Shrewsbury Hospital.
Defence barrister Dafydd Roberts said Yapp had no memory of the attack because of alcohol and was genuinely sorry for what she did.
She had since moderated her drinking, he said.
Judge Saffman said Yapp had intervened in a verbal dispute involving a friend and struck the victim without provocation.
“You used that bottle as a weapon, intentionally, to strike Miss Williams on the head,” the judge told her.
The defendant couldn’t remember a “savage” attack on a defenceless woman, the judge remarked.