Organisers of the East of England Show, expected to take place in Peterborough in July, said 10,000 people attended last year, 50% fewer than expected.
The show "became disconnected from its agricultural roots" organisers the East of England Agricultural Society said.
A spokesman said local people had "voted with their feet".
Chief executive of the society, Jeremy Staples, said: "It was a very difficult decision to make.
"The show had been losing money for a number of years but more importantly, attendance figures had dropped dramatically over the last 20 years."
At its height of popularity the show would have attracted about 100,000 people, he added.
"Last year's show took four months to put on and with fewer than 10,000 people, it clearly wasn't appealing to the local population," Mr Staples said.
The 2012 show was dogged by wet weather which may have been a contributing factor, he admitted.
"There has been a move away from traditional agricultural shows - demonstrating new materials and techniques - so farming people no longer come, and shows such as the East of England have slightly lost their way."
Participants were informed about the cancellation before Christmas, and there will be no job losses as a result of the decision, Mr Staples confirmed.
"We've decided now to go back to our roots, to educate people about farming and rural life. We have 4,000 children coming on 5 July and we have a really good kids' programme we're developing throughout the year," he said.
"We see this as a very positive step."
An agricultural and country show which last year made losses of "several hundred thousand pounds" has come to an end after 200 years.