Supermarket bosses and farmers' unions have warned the Government a so-called hard Brexit would put food supplies in the UK at risk.
Migrant workers and tariff-free access to the single market are vital for the industry, Morrisons, Sainsbury's, Marks & Spencer, the NFU and others have warned.
In a letter to The Times, the group also called for assurances that European Union citizens already working permanently in the country would be allowed to remain.
It comes as claims Boris Johnson privately told European Union diplomats he backs freedom of movement were dismissed as a "total lie".
Four ambassadors say the Foreign Secretary told them he supported unrestricted migration across the bloc, according to Sky News.
"He did say he was personally in favour of free movement, as it corresponds to his own beliefs," one told the broadcaster. "But he said it wasn't government policy."
Sources dismissed the claims as a "total lie" and insisted he had "never said anything of the sort".
Mr Johnson's spokesman said: "Boris said what he has said many times before - he is pro-immigration but wants to take back control to limit numbers.
"He did not say he supported freedom of movement and challenges anyone to show proof that he ever said that."
Labour said Prime Minister Theresa May must "get a grip" to end the confusion around Brexit.
Access to seasonal and permanent employees from overseas is "essential" to the food supply chain in the UK, food industry leaders said.
The intervention from the country's largest manufacturing sector heaps more pressure on the Government over the direction its Brexit negotiations will take.
European leaders have made clear their opposition to giving Britain concessions on freedom of movement if it wants to remain part of the trading bloc.
European Council president Donald Tusk earlier this week also insisted there would be no deal on expats until after the Article 50 process for quitting is formally triggered.
The letter has been signed by the NFU in England, Scotland and Wales as well as the Ulster Farmers Union and 71 food businesses with a collective turnover of more than £92 billion, including Dairy Crest, Arla Foods, Weetabix, Wyke Farms and Muller Milk & Ingredients.
It states: "For our sector maintaining tariff-free access to the EU single market is a vital priority. It is where 75% of our food exports go, so all our farming and food businesses wish to achieve this outcome.
"The sector needs access to EU and non-EU seasonal and permanent labour, alongside assurances that EU workers already working permanently in the UK are allowed to remain.
"This access to labour is essential as it underpins the UK food chain's timely delivery of high quality affordable food to consumers. We would urge that the UK Government seeks both these goals as the whole of society and the economy will benefit."
Farmers fear they will not be able to find the staff they need to pick, grade and pack crops if Britain no longer has unrestricted access to EU workers.
But Mrs May indicated curbing immigration was more important than remaining part of the single market when she gave an update on plans for Britain's departure in a speech to Conservatives in October.
The letter states: "We are clear that the outcome of this negotiation will have far reaching effects for our sector.
"But we are equally clear that a settlement that recognises the critical role of the UK food chain will demonstrate how Brexit can be beneficial not just for our sector but also the wider economy too."