The incident took place yesterday at Yorkshire Halal on Wakefield Road in the town.
The police said they were called to reports of a man having been injured with a knife at Yorkshire Halal at around 11:36am.
A man in his 20s was taken to Leeds General Infirmary by air ambulance for treatment to injuries. He remains in hospital for treatment to shoulder injuries, which are not believed to be serious.
Following enquiries by the police, a man in his 30s was arrested in connection with the assault and is now in police custody.
The scene at the premises was closed and enquiries by Wakefield CID are ongoing.
Yorkshire Halal Meat Suppliers is a privately-owned company, which was originally founded in 1984 by Ali Shan. The business has been on its present site at Ossett since 2001, with the abattoir refurbished in 2002 to provide “a modern hygienic slaughtering facility”, according to the company.
The abattoir produces more than 200,000 ewes and 150,000 lambs per annum. These are mainly sold in carcase form and distributed in the company’s own fleet of 15 refrigerated vehicles.
The meat supplier sources over 90% of its sheep from local markets and farms, where the animals are fed on natural pastures.