Workers at Park Cakes in Bolton and Oldham have voted for strikes over new contracts.
The 1,000 BFAWU bakers’ union members voted by 71 percent to back the action.
The union says the firm brought in contracts with worse pay and conditions for new recruits before agency worker laws came into force.
BFAWU president Ian Hodson said the ballot result “sends the clearest signal yet to Park Cake management and their owners, Vision Capital, that the workforce of both Bolton and Oldham will not tolerate unfairness”.
Park Cakes makes cakes, pastries and desserts for supermarkets including Tesco and Sainsbury’s.
The workers were to hold mass meetings on Saturday of this week to discuss the next steps in their fight.