The Strictly Come Dancing host will play the June 29 to July 1 event at Paddock Wood, Kent, with his Big Band.
Organiser Vince Power said: "I am honoured to have the legend that is Sir Bruce come down and make his debut appearance at the Hop Farm this year.
"Not only as he never appeared at a festival, he's never been to a festival. He has been in this business for over 70 years and is a true, true legend; he will be the talking point of the festival."
Forsyth last year released the album These Are My Favourites, which featured a duet with his granddaughter Sophie Purdie.
The entertainer marks his 70th year in showbusiness next month with a show on May 3 at the Royal Albert Hall
This year's Hop Farm Festival is headlined by Bob Dylan, Suede and Peter Gabriel and the New Blood Orchestra, with support from Damien Rice, Primal Scream, My Morning Jacket, Maximo Park, Patti Smith and more.
A limited number of tickets are available now for £150. Full price weekend tickets are available for £162, while Day Tickets are priced at £55 for the first 5,000.
A separate Day At The Hop Farm event takes place on September 8 and is headlined by Leonard Cohen.
> Bruce Forsyth on knighthood: 'The waiting was torment'
Watch Bruce Forsyth win the 'Special Recognition Award' at the 2011 National Television Awards below: