The Farmers Union of Wales has called for a ‘stay of execution’ for the mart which has been central to the town since 1254.
Glamorgan Council has confirmed Cowbridge Mart will not have its licence to operate the market extended beyond its current end date of March 2020.
The council intends to build a new car park and temporary events space on the site.
Although meetings have been held to discuss relocating the market, FUW was concerned there were no firm plans, potentially leaving Glamorgan without a permanent livestock market.
FUW county executive officer Rachel Saunders, said: “We are very concerned that this move will be the end of market trading in Cowbridge, something which will cost our local farmers, already under pressure because of uncertainty over red meat sales post Brexit.
“Currently the site provides an opportunity to sell stock directly to buyers, but if it closes then the closest alternative is at Raglan, Carmarthen or Brecon and that will mean extra costs for our members,” she said.
She said Cowbridge farmers, who do not have the necessary accreditation, were only allowed to transport their stock for a maximum of 50 km. This means they will have to pay additional haulage costs to sell their produce.
“We are in discussions now with the auctioneers, local farmers and with the council itself.
“Our very real fear is that if the site shuts down the new one will never be built, and currently it is understood that there is no guaranteed funding for the new mart.
“Our aim now is to bring together all the different parties and draw up an action plan in an attempt to ensure that our members have easy access to buyers and the long term future of agriculture in the county is supported.
“As it is, the uncertainty in farming now is causing serious mental health issues within the industry, and this announcement only puts further pressure on a worried community,” she added.