Heinz has confirmed it will close its Westwick factory in Norfolk next year.
The food manufacturer first began consulting on plans to shut the site near North Walsham in October following a decision by the William Jackson Food Group - owner of the Aunt Bessie's Brand - not to renew its licence with the company.
Heinz says, without the contract to manufacture its frozen potato products, there is no longer enough work to keep the factory operating.
A spokesman said attempts to find a buyer for the site had failed.
The factory will continue operating until April 2015, when the Aunt Bessie's licence ends.
Heinz will now focus its efforts on helping workers to find other jobs and will carry on discussing closure plans with unions until at least mid-January.