The 'Bleeding Love' singer – who was reportedly drinking alcohol with pals – had been watching the 'Burn The Floor' musical at the Shaftesbury Theatre, when she amazed theatregoers during a break in the performance when she started re-enacting saucy dance moves from the show and shouting about how she had a crush on one of the show's female dancers.
A source told the Daily Mirror newspaper: "It was hilarious. The rowdy group brought plenty of attention to themselves by re-enacting the sexy lifts and moves from the show during the interval.
"Leona seemed very impressed with Venezuelan dancer Karen Hauer. She kept shouting out: 'She's so hot!' "
The 25-year-old beauty recently split from her boyfriend of 10 years, Lou Al-Chamaa, but has since been flooded with male attention.
She was spotted swapping numbers with The Wanted singer Max George, and went on a date with a mystery man to a zoo in Germany.
However, Leona's new party-girl persona has come as a surprise, as the pop star has previously blasted people who drink alcohol to have fun as having a "stupid mindset".
She previously said: "I find some people's attitude to drinking ridiculous. I think it's so funny that people think you have to drink in order to have fun. It's such a stupid mindset! A lot of my friends are like, 'I need a drink to get on the dance floor!' I don't need that 'help me to relax' thing. If I'm around my friends then I can really relax and have a good time, that's all I need. I don't need alcohol."