The actress stars with Daniel Craig in the latest James Bond film as 007's fellow MI6 field agent Eve.
In a recent interview, Harris said that landing the coveted role came as a total surprise.
"I couldn't believe it, I thought they were having a joke," Harris said, reports Flicks and Bits. "I know that they auditioned thousands of girls, they auditioned all around the world, so I thought I was thrown in there to make up numbers."
She continued: "I didn't think anyone would see me as a Bond girl. For me it's a huge, huge honour because I grew up watching these movies and loving these movies. I truly never thought I would be a part of them. I was so over the moon."
Harris follows in the footsteps of previous Bond girls Ursula Andress, Diana Rigg, Britt Ekland, Denise Richards, Halle Berry and Eva Green.
The star recently described her Skyfall character Eve as "independent, intelligent and courageous".
She has also hinted that a black actor could be cast as James Bond in the future.
Skyfall will be released on Friday, October 26 in the UK and November 9 in the US.
Watch the cast of Skyfall talk to Digital Spy below: