The company, which used to be known as Tinsley Wire, employs just over 400 people at its Sheffield Road and Shepcote Lane works and has had operations on the prominent Sheffield Road site, next to Meadowhall Retail Park, since 1933.
"It's come out of the blue," said one worker, who did not want to be named.
"We heard something a couple of months ago about them selling this site off, but the company dismissed it as wild rumours. Now we're fighting for our jobs."
Personnel chief Jonathan Storer said jobs would be lost from both the Sheffield Road and Shepcote Lane sites over a period of two years and the company was looking at ways of reducing the number of redundancies to possibly as low as 50.
The average age of the workforce at the Sheffield Road site is 48, so the company is anticipating a significant proportion, if not all, of the redundancies will come through people volunteering to take severance and an early pension and seek a less physically demanding job.
Wire drawing equipment from the Sheffield Road site will be moved to Shepcote Lane, where it feeds equipment manufacturing fencing, barbed wire and welded mesh.
Money raised by the sale of the 13-acre Sheffield Road factory will be re-invested in turning the remaining Sheffield site into a world-class facility.
The company says it does not have a buyer for the site, but has had a number of enquiries in the years since the Meadowhall shopping centre and retail park were built and is hopeful there will be a flurry of interest now the plant, which is already largely empty, is being officially put up for sale.
Betafence blames low cost competition from China - where its Belgian owners have set up a plant - Spain and other parts of the world for a decline in demand for chain link fencing and "woven" wire products, which has prompted the redundancy announcement.
However, it says its welded mesh business is thriving.
Steve Stacey, Yorkshire and Humberside regional secretary for Community, the union which represents the majority of Betafence's workforce, said: "We are disappointed by the company's announcement as consultations only began last week and we reiterate that we expect no compulsory redundancies.
"We will be working to ameliorate the effects of redundancies that do occur."
n Betafence was launched last year after Belgian wire products giant Bekaert announced in that it was selling its Dutch-based subsidiary, Bekaert Fencing NV, to the Dutch private equity investor Gilde in a deal that valued the business at €281.5 million - £194.2 million.
The deal included Tinsley Wire's plants in Sheffield and Wigan - which is unaffected by today's announcement. Gilde said at the time it believed the business had potential for growth and would be able to develop new products and reinforce its market leadership.