Dame Prue was hired for Bake Off after the series jumped from the BBC to Channel 4 in 2016.
She replaced Dame Mary, who left the show along with presenters Mel Giedroyc and Sue Perkins after the move.
Channel 4’s chief content officer Ian Katz said Dame Prue had been “a joyous presence in the tent, pairing absolute culinary authority with great generosity and empathy for the bakers”.
“We are grateful for her passion, her wit, her ineffable style, and all the summers she spent in the tent.”
He added: “She leaves an indelible mark on the show and all its bakers. We will miss her wry, gentle judgement but look forward to working with her on new projects.”