The former Pussycat Doll was the epitome of effortless cool in her skinny jeans, loose black shirt and oversized black sunnies on Tuesday morning (13 August), but it was those incredible glossy locks that really stole the show.
Well, she is a brand ambassador for Herbal Essences, so perhaps that's no surprise!
Nicole has been in London filming the bootcamp stage of X Factor's tenth season alongside fellow judges Gary Barlow, Sharon Osbourne and Louis Walsh. Filming for that wrapped on 11 August so now it's on to judges' houses in glamorous locations around the world.
We wonder if Nicole will bring her group to her adopted hometown of Los Angeles? Or even her native Hawaii?
Last year she treated her boys - including eventual winner James Arthur and runner-up Jahmene Douglas - to a trip to Dubai.
Aside from her X Factor duties, Nicole hit the headlines this week when speculation arose that she'd rekindled her romance with Formula 1 driver Lewis Hamilton.
The couple split following a five-year relationship last month but recent reports suggest they've decided to give their love another go after meeting for a heart-to-heart at Nicole's home in LA.
Watch the first trailer for X Factor 2013 below!
From Steve Brookstein to James Arthur: can you remember all the X Factor winners? Pictures!
Copyright: WENN Harsha Gopal