The 'Price Tag' singer celebrated her 26th birthday last night (27 March) by performing a secret gig at Oslo in Hackney, London.
And of course, Jessie ensured she was looking suitably glam for the occasion...
The gorgeous starlet showed off her toned physique in high-waisted trousers and a crop top, adding a suit jacket and strappy heels.
But it was her barnet which really caught our eye. Jessie recently revealed she's been trying to grow her locks out after shaving her head for Comic Relief last year.
And we reckon she's doing a pretty good job!
The songstress styled her jaw-grazing bob in a side parting before tonging into tight curls, which added heaps of body and volume.
If you fancy getting her look, go for a curling wand with a thin barrel to create small curls like Jessie's. We like Remington Pearl Hair Curling Wand, £19.99, which comes with a protective glove to stop your hands getting burnt.
Part your hair into sections, then wrap a narrow piece of hair around the barrel before holding for a few seconds.
Now for the key part. Instead of unwinding your hair from the barrel, simply slip the wand out from one side of your curl (make sure you're wearing the glove for this!)
Using bobby pins, secure this curled section of hair to your head and allow to cool. This will help your tresses stay curled for longer.
Continue all the way around your head, then take out your pins right at the end. Backcomb your roots for added volume before spritzing your new 'do with hairspray (such as John Frieda Luxurious Volume Thickening Hairspray, £5.99) for extra hold.
What do you think of Jessie's hair? Let us know by commenting below as the best comment across the site each week wins £50!
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Watch Jessie J, DJ Cassidy and Robin Thicke's video for 'Calling All Hearts':