Presenter Keeley, 36, revealed that she and husband, radio presenter Johnny I'Anson, are expecting a child during the show last night.
She broke the news after co-presenter Harry Gration and weatherman Paul Hudson presented her with two special gifts - a pair of dummies.
Laughing and beaming with happiness, Keeley responded saying: "Well, I have been eating lots of mince pies over Christmas but there is also a baby here as well."
After the show, Keeley took to Instagram to share the news and joked that she already had two babysitters lined up.
She shared a photograph of her sitting between her two colleagues and said: "Our secret is out..... and at least we have two baby sitters ready and waiting!"
Harry, 68, replied saying: "Many congratulations to you both! Wonderful news.
"Now then, as I married you two, also available for baptisms..."
Keeley, who also presents Countryfile Diaries, replied: "You heard his offer here first!"
The presenter and husband Johnny tied the knot two years ago at Castle Farm near Knaresborough, with Harry Gration conducting the ceremony.
The couple organised their own private music festival on the farm with performances from local bands including Leeds six-piece Hope and Social.
Keeley's father, former Rotherham United footballer Terry Donovan, gave her away.
They had been together for five years and became engaged in the Lake District in summer 2017.