The mum-to-be, 32, shared the news through Richard Branson's website, explaining to her fans that she would not be taking part in a charity event due to her pregnancy.
Holly Branson is expecting twins
"As one of Big Change's Trustees, some of you have been asking why I'm now not taking part in the Virgin STRIVE Challenge myself. Well, Freddie and I are delighted to share the happy news that we are expecting twins!," she revealed.
Holly and Fred married in 2011
In a beautiful sunset ceremony, the couple poignantly tied the knot on the blackened, charred remains of where the Branson's family home stood before a freak lightening bolt burnt it down on 22 August 2011 forcing the family to flee for their lives.
Sharing her exclusive wedding album and speaking only to HELLO! magazine, Holly said in 2012: "Because it is such a dramatic environment, you don't get a sad feeling on the ruins, it's more of an uplifting, wow, a feeling of celebration and a time to reflect.
"Before, we were wondering where to fit that many people to have a proper service, but it was the most obvious big flat open space, it was perfect.
"It's definitely our special place and it looked absolutely beautiful, even thought it was still very rustic – there are still piles of rubble – it was dramatic.
"And it's stunning because you're at the top of a hill so there are incredible panoramic views."