The mathematician, now 32, signed up to the long-running BBC dance show back in 2013, where she was partnered with her now boyfriend Pasha Kovalev, 38.
The blonde bombshell looked sensational at the Strictly Come Dancing launch, showing off her phenomenal figure in a pretty white dress.
Her cleavage took centre-stage in the plunging number, which featured a seriously low-cut neckline to reveal a generous glimpse of sideboob.
Posing for photographers at the star-studded bash, Rachel Riley looked right at home in the flared frock, ensuring all eyes were on her bust in the halterneck design.
She also flaunted her slender curves, showcasing her trim waist in the figure-hugging bodice as she smiled on the red carpet.
The ensemble was complemented by white and gold dance shoes and the Countdown star wore her signature platinum tresses teased into voluminous curls.
Rachel finished the look with dramatic smokey eye make-up, fluttering fake lashes and a touch of gold glitter eyeshadow.
The presenter made it through to week six of Strictly Come Dancing before she was eliminated with her partner Pasha, losing the dance off to Abbey Clancy and Aljaz Skorjanec, who went on to win.
She and Pasha later found romance after she split from her husband Jamie Gilbert.
They went public with their relationship in 2014 and Rachel previously revealed she isn’t in any hurry to tie the knot with the dashing Russian dancer.
“I don’t feel I have to get married,” she told the Daily Express.
“I don’t think I need that pressure anymore. And I am perfectly happy.
“I’ve got a good relationship with my other half,” she said last year. “I don’t worry about getting married or whether he is taking a long time in the morning or whether he has done the dishes.
“That does not really bother me in the long term. I feel settled,” she added.
Rachel’s beau Pasha made an unexpected confession in his 2013 autobiography.
“The first thing I should probably confess is, contrary to what you’ve heard, my name is not actually Pasha,” he wrote.
“In Russia, where I was born and grew up, everyone has a couple of names,” he explained.
“There’s your ‘real’ name, the one that’s used on all your formal documents (and sometimes when you’re in trouble), but you’re never really called that by anyone you know.
“And then there’s your ‘nickname’ — in my case, Pasha.”
Pasha revealed his family had put names into a hat and drawn one out when he was born and that his real name was actually Pavel.