Officers were called to a Shortland St address in Wainoni about 8.45pm on Monday. Both ends of Shortland St were blocked off during the incident.
It is understood the woman was hit in a drive-by shooting, and may not have been the intended target.
The shooter then fled in a vehicle and police have been searching for them since.
Detective Senior Sergeant Jo Carolan said in a statement this morning police "would like to reassure the community this is believed to be an isolated incident with no increased risk to the public".
"The victim sustained a single gunshot and is in a stable condition in hospital.
"Police are concerned around the dangerous and violent act in public and have an increased presence in and around Christchurch as officers carry out reassurance patrols."
Carolan urged anyone with information on the incident to call police on 105, quoting file number 251110/6195.
