The former Pussycat Dolls star mentored Matt to victory on The X Factor last weekend, and on Wednesday night they reunited in the capital for a bite to eat at Zuma.
Nicole, 38, looked gorgeous in her black mini skirt and white shirt, teamed with a biker jacket, hat and heels, while Matt, 23, was looking dapper, having earlier attended The Sun Military Awards.
The pair formed a close friendship during their time together on X Factor.
"I'm just so happy for Matt. I'm over the moon," said Nicole. "I feel like I've won X Factor too! All that hard work and everything has paid off. You either have it or you don't, you're born with it or not, and he was."
"I'm so happy he got to shine, take it all in and embrace it," added Nicole. "When he was up there, I felt it. I believe it. It's just magic. It was magical."
Matt's now signed a record deal with RCA Sony and released winner's song, 'When Christmas Comes Around', which has already topped the iTunes chart. The track was written by Ed Sheeran.
"I just want to meet [Ed] and give him a massive hug, tell him how much of a genius he is. I don't think I could ever thank him enough, it's just unbelievable," said Matt on yesterday's BBC Radio 1 Breakfast Show.
100 per cent of profits from the sales of the song will be split between charities Together for Short Lives and Shooting Star Chase.
"These charities help kids who have been born with disabilities, disadvantages and illnesses," explained Matt. "Of course I would love a number one, that would be absolutely insane, but mainly I want it to do well for these two charities. I got to meet a few of the kids throughout my X Factor journey and it would be great for them."
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