Employers including the Canberra Innovation Network, Blueblood Solutions, Community Shapers, Capital Brewing Co and the Australia Institute are among those supporting the strike and allowing employees to march alongside school students on Friday, with many offering extended lunch breaks or even the whole day off to mark the day.

ACT government employees have also been told they can join the strike, which has the support of 30 unions.

Michael Reid, owner of information technology business Blueblood Solutions, said he had long been concerned about climate change.

"I figured it was time to get off my butt and attend some of these rallies because voting doesn't seem to be getting us there," he said.

Mr Reid has a small business, with five people in the office most days, but by agreeing to close the office for the day and telling his clients only emergency work would be responded to, there has been an opportunity to spread the message.

"We sent out an email a week and a half ago to say this is what we're doing and a number of clients replied and said 'we've signed up now'.

"One came back and said 'Are you sure you want to do this, you're being a bit dramatic?' but it's at the point where we need to be a bit dramatic."

Mr Reid and his employees will be taking a phone and a laptop on Friday to respond to any IT emergencies if needed.

Asked about the financial impact of paying his staff to not work for the day, Mr Reid said he hadn't given it much thought as it was the right thing to do.

Phoebe Howe from Community Shapers, a Canberra call centre that has many non-government organisations as its clients, said the 40 staff had been encouraged to go to the march, with casual staff able to move their shifts to be able to attend without feeling a hit to their pay-check.

If it takes slightly longer than usual to get a beer at Capital Brewing on Friday lunch, it's for a good cause the business believes, with all 46 staff given the option to attend the strike, with skeleton staff staying on deck at the bar.

The Canberra Innovation Network is also supporting its staff to attend the march with chief executive Petr Adamek saying they are lucky to be supported by a progressive local government.

"We are surrounded by entrepreneurs building businesses that can make an impact and change the world. Innovative startups are leading this change in sustainability, agriculture, waste management, and smart technology that can track the footprints we are leaving.

"We support these entrepreneurs on their startup journey, and we support them if Friday is part of that journey."

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After a week in which Prime Minister Scott Morrison and assistant minister Ben Morton called for businesses to stop advocating for social causes, chief executive of the Canberra Business Chamber Michael Schaper said it was up to each business what causes they spoke out on.

"Every business is free to make their own choice about whether they see something as important and whether they speak out on it," Mr Schaper said.

Businesses could make those statements both through activism and other ways, like investing in sustainable options, Mr Schaper said.

"Increasingly employees are attracted to a business not just because of career opportunities but because of the values they talk about and act upon, and that's something businesses take into account when they choose to participate or not."

Mr Schaper said the Canberra business community was somewhat different to the business community more widely, with local businesses accepting the science of climate change and the need to act.

"Here it's like, we all know that, next question or next step."

A survey by the Committee for Economic Development released on Monday showed 78 per cent of the public wanted corporate leaders to speak out on issues of national importance, including social and environmental issues.