The group has sent a letter to companies including Coca-Cola, Heinz, Kraft and McDonald's, saying its 57,000 members will be urged to boycott them if they oppose the proposed tax, News Limited reported on Friday.
The letter said members will be "urged to boycott goods and services that are linked to the scare campaign".
Get Up was responding to reports the Australian Food and Grocery Council, which lobbies on behalf of many food producers, has signed up to a group campaigning against the government's carbon tax package.
Other companies that received the letter include Schweppes, Nestle, Arnotts, Colgate-Palmolive and Johnson & Johnson.
Chief Executive of the Australian Food and Grocery Council, Kate Carnell, described the letter as blackmail and bullying.
