They worked in different areas of the Wombwell plant, in Valley Park Industrial Estate.
In total there has been nine confirmed cases of Covid-19 among the 1,200 employees at Cranswick Convenience Foods, seven of whom had to be hospitalised.
Of them, three have died, two have been discharged and are back at work, and one has been discharged, but remains off work with non Covid-19-related symptoms.
One person remains in hospital, and is believed to be making good progress.
A spokesman for the Hull-based pork, sausage and bacon producer said health and safety was their "number one priority".
From the outset of the pandemic they had implemented extra measures to protect their workforce who were "at the forefront of maintaining vital supplies of fresh food into the supermarkets".
Staff have been offered face visors at the site in Barnsley which makes sliced, cooked meats.
The spokesman said: "Sadly, three of our colleagues have passed away with Covid-19. Our thoughts and condolences are with their families and we are providing full support to them and to all of our colleagues directly affected by Covid-19.
“From the outset of the pandemic, we implemented additional measures to protect both the physical and mental wellbeing of our people, including social distancing measures where practical, recommended PPE for all employees in line with PHE and WHO guidelines, additional cleaning and hygiene measures, as well as support such as counselling and occupational health services.
"All colleagues are also advised not to attend work if they have any symptoms."
They were working with the relevant authorities, including the Health and Safety Executive, Public Health England, Food Standards Agency and local environmental health officers.