Food manufacturer Kerry Foods have earmarked its factory in Burton-on Trent for closure, putting 900 jobs at risk.
Union officials have described the plan as a "crushing blow" for the area.
Unite said it would leave no stone unturned in helping its members affected by the announcement, and has already been in touch with brewer Molson Coors, the town's second largest employer, regarding employment opportunities.
Regional officer Rick Coyle said:
Unite said the closure was a result of Kerry Foods losing its contract to supply supermarket giant Tesco with ready-made meals
Mr Coyle added: "The problem going forward is that there are not that many well-paid jobs in Burton and the vicinity to replace those that will be lost at the end of August.
"We have been in touch with Molson Coors to explore employment opportunities there. Also, we will help arrange a jobs fair at the site and assist our members with their CVs and advice on updating their skills."
In a statement a spokesperson for Kerry Foods said:
The union said its staff will meet management on Friday to discuss an enhanced redundancy package for its members.