The bubbly 28-year-old will share presenting duties on the ITV show with her Phillip Schofield, her Dancing On Ice co-host.
"To spend my days sat next to Phil on the sofa just makes it that bit extra special," enthused Holly, who recently welcomed her first child with husband Dan Baldwin. "Now I just can't wait for it all to start."
Her tenure on the early morning talk show won't begin until September after the programme goes off-air for summer. Fern will present her farewell episode on Friday.
On Thursday as soon as news of the deal broke Phil paid tribute to his outgoing partner and her replacement. "Everyone adores Fern and will miss her enormously but Holly was at the top of the list to pick up where Fern leaves off."
He added that his new colleague had already been in the studio: "Where we all had a couple of bottles of bubbly".
Don't forget to check out hellomagazine's celebrity Twitter page for more star 'Tweets'