'I cannot be more grateful to Eugenie's grandmother for making this day so memorable,' she told Hello magazine.
'I am so grateful for all the hard work and kindness behind the scenes to make such a special day for our daughter.'
Fergie also expressed how proud of her daughter she was for showing her scoliosis scar from a childhood operation.
'I was so proud of Eugenie standing tall and showing her scar. She is an inspiration to young women everywhere,' she added.
Prince Andrew also explained that it was The Queen that decided on the cost and the scale of the wedding.
'It doesn't make any difference who you are, all the approvals go through the Queen anyway,' he told ITV’s This Morning show.
'The Queen very firmly said St George's is where you're having the wedding, so I said aye aye mam, turn to the right, salute and carry on,’ he added.
Sarah Ferguson has always shown her admiration for The Queen and has previously expressed her respect for her mother-in-law, despite divorcing Prince Andrew over two decades ago.
The queen and I always got on well, still do,' she told Harpers Bazzar. I uphold everything Her Majesty represents, has given up her life for. For her country, she's selfless to the grave.'