At least 180 jobs are at risk at Adelie Foods sandwich and snack factory in Kilmarnock.
The company plans to close the site in East Ayrshire and move production to its London factories.
Jobs at the nearby Munro Place distribution centre, which employs approximately 50 staff, are also under threat, while some roles will move to other parts of the organisation.
Staff at the factory in Rowallan Business Park were told the news on Thursday morning and Adelie Foods said in a statement it followed “two years of operational investments”.
Martin Johnson, CEO of Adelie Foods, said: “We have reviewed our factory estate to ensure that it is the right size and profile for our future needs, taking into account the nature of our sales growth and the efficiency that has been delivered operationally.
“As a result of this we are proposing to move all production from our Kilmarnock factory to our southern sites in Wembley and Southall.
“This proposal to close our Kilmarnock factory has been made after significant and careful consideration.
“Kilmarnock has been an important part of our business in servicing our customers in Scotland.
“However, with the recent investment now complete, we have the ability to service each customer from our remaining three factories and our existing distribution centre in Kilmarnock.”
The company will now enter into a period of consultation with employees at Kilmarnock and Munro Place and will be talking with them and their representatives over the coming weeks.