Australia's two largest supermarket chains, Woolworths and Coles, will make COVID-19 vaccination a condition of employment nationally.

Supermarket giants Woolworths and Coles plan to order their combined workforces - about 300,000 people - to get fully vaccinated against COVID-19.

Woolworths want all of its 170,000 workers to get their second dose of a COVID-19 vaccine by early next year to reduce the risk of infection.

The directive will apply to employees at about 1200 stores as well as distribution and online fulfilment centres and support offices.

"With each store welcoming an average 20,000 customers a week, a single team member can come into contact with quite literally thousands of people in the course of a normal working week," CEO Brad Banducci said on Thursday.

"After careful review of the best medical advice, we've made the decision to require all of our team members in Australia to be fully vaccinated against COVID-19."

Workers must be fully vaccinated in the ACT, NSW, NT, Victoria and WA by January 31, and by March 31 in South Australia, Tasmania and Queensland.

But Woolworths also recognises some workers might have legitimate medical or religious reasons to be exempt.

It's planning a series of workplace meetings before making a final decision on its double vaccination plan in November.

About a third of its Australian workforce is already subject to state-issued health orders requiring full or part vaccination in order to work.

In the coming months, Coles will require workers to be vaccinated as a condition of working at stores, distribution centres and other sites in NSW, the ACT and Victoria, unless they have a valid exemption.

Government health orders also require Coles staff in the NT and Coles supermarket workers in WA to be vaccinated in order to work.

Coles says it will work with team members in those jurisdictions so that they can comply with the regulations.

"We have worked hand-in-hand with health authorities and adopted their recommended safety measures, allowing us to keep our 120,000-plus team members and millions of customers safe," Coles Group CEO Steven Cain said in a statement.

As part of the new requirements, Coles workers in NSW and the ACT must have had at least one vaccination by November 5 and their second dose by December 17.

In Victoria, NT and WA, team members are required to be vaccinated in line with the dates set out in public health orders.

In each state where employees are required to vaccinate as a condition of work, either as a result of government health orders or as part of Coles' policies, Coles intends to maintain this as an ongoing requirement.

Both chains will not require customers to be fully vaccinated to buy food and other goods - which is in line with current state-based health orders.