The shooting happened in Visions, in Kingsland Road, Dalston, just before 5am.
A man pulled out a gun and approached another man in the club.
There was a struggle and the gun was fired, with the bullet striking the innocent 28-year-old woman in the leg.
She was taken to hospital and although she was discharged, she is still receiving medical treatment.
On Wednesday, detectives released photos and CCTV footage of the suspect, who has a distinctive tattoo on his neck.
He is described as black and aged about 30. The tattoo, on the right side of his neck, has the word “God” followed by a longer word that begins with “Bless”.
Det Cons Kerry Cooper said: “This man went armed and discharged a firearm in a crowded club. As a result of his recklessness an innocent woman was shot in the leg, but the consequences could have been fatal.
“We urgently want to arrest this man and take this weapon off the streets. Anyone with information should not hesitate, but call police immediately.”
Witnesses or people with information are asked to call police on 101, quoting CAD 3029 of January 1. Alternatively, call Crimestoppers anonymously on 0800 555 111.
