The former Destiny's Child singer swears by body-shaping underwear and believes it can transform any body shape! Unusually for a star, she also likes to be comfortable on a night out and consciously avoids sky-scraper heels because they make her look "a whole lot of crazy".
"Spanx are every girl's best friend," she said. "And always make sure you're comfortable in whatever you're going out in, it's so important."
"If you're going out in six-inch heels, make sure they're ones that you can last at least seven hours in. Because when you start walking like there is a watermelon between your legs because your feet hurt so much, you look a whole lot of crazy."
Kelly – who is currently a judge on the UK version of X Factor – also gave us some beauty advice, saying, "I always choose a great lipstick because it really makes an outfit pop.
Read Kelly's tips for a great body here.
"Even if you have an all-black outfit on and you pair it with a bright pink or red lipstick or something, it looks great."