Domestic violence victims seeking anonymous help can disguise a search for help to look like online grocery shopping.
Countdown has joined a Women's Refuge initiative called the Shielded Site, an online tool which provides support and information within host sites.
The supermarket chain joins a group of New Zealand businesses including The Warehouse, ASB Bank, Sorted and Z Energy who have added the tab to their sites.
The Shielded Site doesn't leave a trace in a user's browser history, meaning victims can safely access the help they need without a controlling partner being able to find out.
It was created for Women's Refuge by Saatchi and Saatchi late last year in response to a growing number of abusers controlling their partners by monitoring their internet use.
The Shielded Site is an iFrame portal which appears as an icon on a partner's website.
When a victim clicks on it, a small window overlay containing the Shielded Site (a slimmed down version of Women's Refuge's most critical contact and safety information for those suffering from abuse) will appear.
The site can then be closed just as easily - without affecting activity on the host site.
Anyone in an abusive relationship who is seeking support or advice can now safely visit the Countdown website, click on the Shielded Site icon, and be provided with vital information without leaving a browser trail.
Women's Refuge CEO Dr Ang Jury said Countdown's adoption of the Shielded site was "hugely significant" for the initiative.
"When we launched, our ambition was to have the Shielded Site available everywhere and importantly, in the places people would visit in the course of a typical day.
"With Countdown being one of New Zealand's most visited sites we're now able to safely connect with thousands more people who could potentially need our support."
With 120,000 visits to its site each week, the chain had a huge reach within the New Zealand population, including domestic violence victims, said Countdown's head of online Sally Copland.
New Zealand has the worst family violence rates in the developed world with one in three women experiencing abuse at some stage in their lifetime.
While technology created new pathways for victims to leave violent situations, abusers were also finding new ways to control and manipulate their partners, such as using GPS location to track their victims, obtain their victim's email or banking passwords or even checking their web browser history to monitor them.