The weather presenter, who worked with Harry on Look North, posted a picture of her, Harry and husband Johnny l'Anson on their wedding day with an emotive message.
Keeley is the latest of thousands of people to pay tribute to Harry after his death was announced by a tearful Amy Garcia at the end of Friday nights show.
Scores of former colleagues have also come forward to pay tribute, describing him as a 'outstanding broadcaster and a proud Yorkshireman'.
On her instagram, alongside a picture of the the three on their wedding day, she wrote: "This is the day @mrharrygration married us, our dear friend. I remember when we asked him he cried. He treated me like his daughter at Look North.
"He was so kind and generous, always sneaking off to pay for meals but also in the time and opportunities he gave me on air.
"I’m so dreadfully sorry for your lovely family and I’m so sad I won’t see you again Harry. Love you x"