The firm says despite investing heavily in the site over the last four years in an attempt to stem huge losses, the factory has continued to record unsustainable losses.
The company today announced to staff it was beginning a 90-day consultation exercise with its unions and workers.
Vion UK chairman Peter Barr said: "This is an extremely sad day and one we have strenuously tried to avoid for the past four years, but the huge losses being incurred mean we believe we have no alternative.
"Every possible step has been taken to secure the future of the business but we are currently losing £79,000 per day at the site, which is clearly unsustainable.
"There is significant over-capacity in the UK meat industry and market conditions are extremely challenging."
The latest accounts for Vion UK companies show a significant deterioration in financial performance compared with the previous year.
Mr Barr added: "Over the past four years, we have restructured this plant, invested heavily in the site and have brought in new management from across the group in an attempt to stem the losses, which have arisen in part due to the complexity and inefficient layout of the plant. Regrettably the plant remains very heavily in the red despite our best endeavours.
"We have also invested significantly in a modern apprenticeship scheme at the plant which attracted the offer of grant support from the Scottish Government. While we were extremely grateful for the support offered, clearly, in the circumstances, we have not and will not be drawing on those funds."
The plant was purchased by Vion in August 2008 when it acquired the troubled Grampian Country Food Group, which had been in financial difficulties for several years.
Hall's of Broxburn, employing 1150 permanent and 595 agency staff, is the major processing facility for Scottish pork, handling 8000 pigs each week.
West Lothian Council leader John McGinty said: "It is a shock to hear the scale of the potential job losses in Broxburn. We understand the company has made significant changes across Europe following ‘disappointing results’ in 2011. It is a devastating for everyone involved. VION is a major employer in the area and this is undoubtedly a serious blow in what is already an extremely challenging employment market.
"West Lothian Council will work with partners through PACE (Partnership Action for Continued Employment) and with local communities to do everything possible to help the people and families affected by today’s announcement. West Lothian Council will play a key role in any task force which is established by the Scottish Government and will be pressing for a clear explanation from Vion on how the current situation has been allowed to happen and what can be done to preserve the plant and local jobs."
Local MSP Fiona Hyslop said: "This is a devastating blow for workers and their families in West Lothian. Vion Hall's is the biggest private employer in this constituency and there are many experienced workers with expertise in food production in the company and we must make every effort to try and secure a positive outcome."
Ms Hyslop will be attending a rapidly convened Government-led Task Force later on this evening as the local MSP.
She added: "I call on everyone concerned; management, unions, the workforce, enterprise agencies, Government and Local Council to pull together to tackle the enormous challenge facing West Lothian.
"The Hall's site has been under threat on a number of occasions over recent years before Vion Halls took it over in 2008.
"Vion appears to have been unable to resolve this situation due to internal changes within its company and increased demands in production at the Broxburn site, resulting in substantial losses which has led to this situation. The workforce, however should not have to pay the price.
"We must all pull together for the good of the workforce to support the West Lothian economy and as the local constituency MSP I will do everything I can to assist."