The UK is to offer Australia a trade deal under which both countries would phase out taxes on imports over the next 15 years.
The cabinet was reportedly split on what terms to offer, amid concerns UK beef and lamb farmers could be undercut by larger Australian producers.
But Boris Johnson pushed for unity at a senior ministers’ meeting on Thursday.
Downing Street said the cabinet was now in agreement, while negotiations with Australia were still “still ongoing”.
The government is keen to strike as many trade deals as possible following Brexit, and International Trade Secretary Liz Truss wants one in place with Australia by early June.
But she had reportedly been at odds with Environment Secretary George Eustice over the possible impact on farmers.
Speaking on a visit to a bakery in north London, Home Secretary Priti Patel said: “The government is united on every single level. We are working at every level to secure the best outcome for our country.”
She added that “the government will work with everybody – everyone – to ensure that the right sort of support and measures are in place”.
Under the deal set to be offered to Australia, tariffs – taxes on imports – will be phased out over 15 years, with quotas – limits – on sales between the two countries going over the same period.
In 2019-20, trade in goods and services between Australia and the UK was valued at £20.1bn, and both sides are hoping to expand this amount considerably.
Currently, metals, wine and machines form the biggest goods exports from Australia to the UK, while Australia’s main UK imports are cars, medicines and alcoholic drinks.
Trade in meat between the two countries is very small, but the National Farmers’ Union has warned that pitting small-scale UK beef and lamb producers against vast Australian cattle and sheep stations could force many of them out of business.
Approximately 0.15% of all Australian beef exports go to the UK, and, last year, 14% of sheep meat imports to the UK came from Australia.
The Scottish and Welsh governments have both urged Mr Johnson to ensure UK farmers are not left exposed by any free-trade deal.
The prime minister’s spokesman said: “Any agreement would include protections for our agriculture industry and won’t undercut UK farmers.
“We want a deal that is good for the British public and any agreement would have protection for the agriculture industry.”