Sponsored by the National Trust and investment management firm Quilter Cheviot, the event will bring the TV programme to life through various animal and farm-themed activities.
Marks and Spencer and Citroën will be among the 500 exhibitors at the show, and a number of brand activations will be held over the stately home's site.
The National Trust will run a series of free talks and panel discussions about issues affecting the countryside at its theatre, meanwhile, Mitsubishi Motors has created an off-road course where visitors can try out its 4x4 pick ups, including the new L200.
Over at the Tractor Ted zone, children will be able to take their own mini driving test and play on a bouncy castle shaped like the TV character.
The event will also include a street food market, a beer garden and an ice cream parlour complete with 40 different UK producers, including Mackies.
The main stage will seat 4,000 for the arena show For the Love of Farming, featuring presenters from Countryfile. Presenter Adam Henson will also bring elements of his own farm to the experience, showcasing rare breeds and livestock seen on the programme.
The venue will also host the annual Wainwright prize, which celebrates the UK's nature and travel writers.
Announced in July last year, Countryfile Live is being produced by exhibition company SME London.
Stephen Davies, director of live events at BBC Worldwide, said: "Bringing Countryfile to the public in this unique way is something that we’ve wanted to do for ages – we are really excited about bringing fans even closer to one of the most loved shows on the BBC – a cornucopia of countryside related content which we can’t wait for the audience to explore at close quarters."
Tim Etchells, managing director of SME London, added: "With an average of over six million viewers, year-round, each Sunday night, it’s clear that Countryfile is one of the nation’s best-loved brands and we’re looking forward to seeing that fantastic spirit and content brought to life at Countryfile Live.
"One of the most exciting things about Countryfile Live will be the incredible scale of the event. With over 500 exhibiting companies and so many amazing features there is so much to see and enjoy that visitors will be spoilt for choice."