It was sealed late on Wednesday (20 October) via a video call with New Zealand Prime Minister Jacinda Ardern - although the deal has not yet been signed.
While Mr Johnson and many business leaders heralded the announcement, not everyone is pleased.
Farmers fear their produce will be undercut on price, while environmental groups have expressed concern at New Zealand’s sustainability credentials.
So, what is in the free trade agreement, what will it change - and does it threaten British food production?
Here’s what you need to know.
What’s in the UK-NZ trade deal?
The agreement in principle covers more than 30 areas, including food, animal welfare and financial services.
Tariffs (the taxes or duties put on top of the cost of imports and exports) as high as 10% would be removed from a range of goods, including clothing and footwear, buses, ships and bulldozers, according to the Government.
It claimed that while trade with New Zealand was worth £2.3bn last year, this new deal would grow that figure while also giving the UK an advantage over other nations in a market it said was expected to grow 30% over the next decade.
In the UK, the most notable difference for consumers will be seen in their food shops.
The price of some of New Zealand’s best-known products - like Sauvignon Blanc wine, Manuka honey and kiwi fruits - is expected to go down.
Shoppers will also have greater access to New Zealand dairy, red meat and horticultural products, which will come to the UK in ever increasing volumes over the next 15 years before gaining potentially unlimited access to UK consumers after the 15-year mark.
There is also the prospect that New Zealand could become a major destination for gap-year students as UK residents will be able to work more freely in the country.
One of the most eye-catching elements of the deal is an agreement for the UK to advance the recognition and protection of the New Zealand Haka - the ceremonial dance most usually seen before international rugby games involving New Zealand.
What they said
Mr Johnson said the deal would “benefit businesses and consumers across the country, cutting costs for exporters and opening up access for our workers”.
He said: “This new deal will help drive green growth here and on the other side of the world in New Zealand.”
However, the World Wildlife Fund for Nature (WWF) called into question the sustainability of New Zealand’s farming industry.
Angela Francis, WWF chief advisor on economics and economic development, said: “While New Zealand is one of the leaders on many aspects of environmental action internationally, they still have a long way to go to put their agriculture sector on a sustainable footing.
“As we see more and more trade deals coming down the pipeline, the clearer it is that the UK needs a written trade policy to explain how these trade deals align with the overarching economic plan to decarbonise the UK economy and its supply chains.
"As part of this, we urge the Secretary of State to adopt core environmental standards for all food sold in the UK, sending a clear signal to international partners that we are not prepared to undermine the UK’s transition to greener farming by importing products produced in ways that harm the planet."
Food itself is also a controversial aspect of the deal.
This is because both countries’ farmers tend to operate at a scale that far exceeds that of UK producers and also do not have to adhere to the same stringent animal welfare rules that exist in the UK - in NGO World Animal Protection’s Animal Protection Index, the UK has a ‘B’ ranking, while New Zealand has been given a ‘C’ and Australia a ‘D’.
Both of these factors mean their cost of production is usually much lower than it is for a UK farmer.
National Farmers Union (NFU) president Minette Batters said: “The government is asking British farmers to go toe-to-toe with some of the most export orientated farmers in the world, without the serious, long-term and properly funded investment in UK agriculture that can enable us to do so.
“This is the sort of strategic investment in farming and exports that Australian and New Zealand governments have made in recent decades.
“The fact is that UK farm businesses face significantly higher costs of production than farmers in New Zealand and Australia, and it’s worth remembering that margins are already tight here due to ongoing labour shortages and rising costs on farm.”
Batters added that the viability of “many British farms” could be damaged as a result of this deal, which would in turn mean less British produce on supermarket shelves.
Despite these concerns, UK businesses have been largely supportive of the announcement.
Mike Cherry, national chair of the Federation of Small Businesses, explained: “It’s fantastic to see progress being made on a free trade agreement with New Zealand.
“New Zealand has long been a priority market for UK’s small exporters – more than a quarter of which already sell there – and we welcome efforts to build on existing trade ties that go back many decades.”
The Confederation of British Industry (CBI) also praised the news as it could smooth the path for a deal with the lucrative Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), which includes countries like Mexico and Canada.
Overall, trade policy expert David Henig wrote on Twitter that he believed New Zealand stood to gain the most from the deal.
Why is the UK signing trade deals?
This is partly because the UK’s ability to sign its own trade agreements was seen as a key benefit of Brexit, but it has also come out of necessity.
No longer having access to the deals signed by the EU means the UK has to pursue its own agreements to buy goods from and sell goods to other countries at favourable prices.
A message from the editor:
Thank you for reading. NationalWorld is a new national news brand, produced by a team of journalists, editors, video producers and designers who live and work across the UK. Find out more about who’s who in the team, and our editorial values. We want to start a community among our readers, so please follow us on Facebook, Twitter and Instagram, and keep the conversation going. You can also sign up to our email newsletters and get a curated selection of our best reads to your inbox every day.