The Strictly Come Dancing favourite looked sensational in a slinky red dress that highlighted her phenomenal physique.
In the Instagram upload, Alexandra, a former X Factor winner, ensured all eyes were firmly on her in the daring silk number.
She drew attention to her perky bosom in the low-cut frock and showcased her toned arms in the strapless garment.
Raising the hem of her gown, Alexandra gave fans an eyeful of her shapely thighs and stylish heels.
The singer oozed confidence in the fabulous attire as she stared down the camera lenses and struck a sultry pose.
Resting one hand on her chest, Alexandra made sure her sparkling engagement ring took centre stage.
The pop star confirmed her engagement to long-term boyfriend Joshua Ginnelly via Instagram last month.
In a lengthy post, she wrote: “I said YES! Smiling as I type this because it was the best day ever in Paris and so unexpected.
“My soul mate and my love asked me something that I could only have dreamt of. Being in love is one of the most magical feelings life has to offer.
“So grateful for this amazing man in my life, who has supported my family and I through so much. We decided to keep this between us for a while to enjoy this special moment and that’s why we haven’t said anything.
“Something so amazing honestly felt so overwhelming because there was only one person I wanted to call when it happened. I know she is smiling and very happy for us both – because little did I know she knew about it.”
She continued: “For those who guessed and have left such beautiful messages – thank you. Josh is someone who makes me so happy and I’ve never felt this kind of love before.
“Here’s to an amazing future that’s filled with love, joy and so much happiness. I love you Joshua Ginnelly. I can’t wait to see what our future brings and what God provides for us.”
Last week, Alexandra sent her fans into a frenzy when she uploaded a picture of herself in a white dress to Instagram.
Some of her 162,000,000 followers quickly suggested that she was preparing for her wedding day.
One wrote: “A few months and it will be YOUR NIGHT!” While another asked: “Ready for wedding?”
A third commented: “Looking gorgeous Alexandra,” and a fourth user posted: “That dress! Fabulous.”