Spencer, who has played matriarch Peggy Woolley (formerly Archer) since the show’s first episode in 1951, said it was a “high time” she bowed out of the role.
The actress has already recorded her last episodes for the much-loved drama, which were broadcast on July 31.
Spencer said: “In 1950 I helped to plant an acorn. It took root and in January 1951 it was planted out and called The Archers.
“Over the years it has thrived and become a splendid great tree with many branches.
“But now this old branch, known as Peggy, has become weak and unsafe so I decided it was high time she ‘boughed’ out, so I have duly lopped her.”
Peggy was often viewed as a traditionalist, a conservative character in the long-running drama charting the ups and downs of life in fictional Ambridge.
Among Peggy’s many fans is the Duchess of Cornwall, who last year invited Spencer and her co-stars to Clarence House for a reception marking the show’s 70th anniversary.
Camilla also made a cameo appearance as herself in a special episode marking the 60th anniversary of the show.
In a statement, Camilla called Peggy “a true national treasure who has been part of my life, and millions of others, for as long as I can remember”.
Although Peggy has not yet been written out of the show, Spencer has her own ideas on how best to manage her character’s exit.
She told the Telegraph: “The simplest thing is if (Peggy has) a fall or something and goes into The Laurels (the fictional care home in Ambridge).
“She can languish for years there.”
After 70+ years as Peggy Woolley, June Spencer bids farewell to Ambridge. The Duchess of Cornwall said: "Peggy is a true national treasure who has been part of my life, and millions of others, for as long as I can remember..." #TheArchers
Read more ➡️ https://t.co/2i3tFigHdO pic.twitter.com/4tCG8yxOzh
— BBC Press Office (@bbcpress) August 8, 2022
Jeremy Howe, editor of The Archers, said: “I think working with June Spencer has been one of the greatest privileges of my many decades in drama.
“Her Peggy is one of the great creations of broadcasting – utterly charming, utterly ruthless, sharp as a knife and witty in spades.
“To think that June has commanded the airwaves over an Archers career of over 70 years beggars belief.
“I have rarely worked with such an inventive, focused and technically brilliant actor, or such a lovely person.
“Myself and the Archers team and cast wish June a well-deserved and long retirement – and I know that if she doesn’t think the show is up to the mark, June will be letting us know. Bravo the legend that is June Spencer.”
After a few years of playing Peggy, Spencer took a break and Thelma Rogers replaced her in the role. She returned in 1961 and has remained in the role ever since.
Spencer was made both an OBE and a CBE for her services to drama and charity.
In June 2010, she also received the Freedom of the City of London and was awarded a Lifetime Achievement prize at the 2014 BBC Audio Drama Awards.