Daly (43) told Hello! magazine she had no idea she had so much cleavage on display until she saw herself on the programme's sister show It Takes Two.
"I went, 'Oh my God, why did nobody tell me about the boobs?'," she told the magazine.
"What happened was, the bra I had on didn't fit the dress so I wore one of those designs that has gel at the sides, which kind of pushes you up and, I guess, gives you an extra couple of cup sizes.
"I don't usually show a lot of cleavage, it's not in my comfort zone. That'll be the first and last time. The people at home don't want to see that, it's distracting."
Her appearance in the plunging Suzanne Neville evening gown caused a stir among show fans who posted thousands of messages online about her busty look.
Daly, a former model, also revealed she tried to persuade husband Vernon Kay to take part in this year's Strictly Come Dancing Christmas special, which will feature former football star Fabrice Muamba.
She said of her husband: "He's got rhythm. Unfortunately, he's doing the All Star Family Fortunes Christmas special on the same day. It's a shame because he really can move."
Daly, who co-hosts with Bruce Forsyth, also wants Zara Phillips to take part in the festive show.
"I think she'd be really committed and people would get behind her. If she says yes, that would be fantastic."
Meanwhile, Olympic gold medal-winning cyclist Victoria Pendleton has become the latest celebrity to leave Strictly Come Dancing. She and her partner Brendan Cole lost a dance-off against former England cricket captain Michael Vaughan and Natalie Lowe after the judges' scores were combined with the results of the viewers' votes to decide the lowest scoring two couples.
Judge Craig Revel Horwod chose to save Vaughan, saying: "Well this couple completely smashed and I thought they were fantastic, Michael and Natalie."
His colleague Darcey Bussell also chose Vaughan, saying: "Yes, I am going save Michael and Natalie."
Bruno Tonioli made the same choice.
Pendleton said: "It's been so much fun. I have loved every second of it. It pushed me totally out of my comfort zone which I think you really need to do in life."