The siblings, who found fame in The Only Way Is Essex, posed for pictures on the red carpet at London's O2 Arena before heading inside to watch the show.
Michelle is believed to be busy working tonight, but we're sure Mark and Jessica are having a great time together!
While Mark played it cool in a black T-shirt and jeans, teamed with a camel coloured coat, Jess upped the ante when it came to her style.
The TOWIE star opted for a black and yellow strapless dress, metallic shoes and a black choker. Jess kept her hair in loose waves and topped off her outfit with a dark berry lip.
Unfortunately, every girl's worst nightmare happened when someone else turned up in the same dress...
4Music presenter Maya Jama was also wearing the identical frock when she too posed for pictures on the red carpet.
But we've all seen Sex And The City 2, right? Samantha Jones and Miley Cyrus prove that this doesn't always have to be a disaster. You both looked gorgeous, girls!
BRIT Awards 2016