Mariah Carey's romance with her backup dancer Bryan Tanaka appears to be getting serious.

The Hero singer has swiftly moved on from her failed engagement to billionaire James Packer, which ended after nine months in October (16), and into the arms of her long-time dancer Tanaka.

After going public in December, Carey and Tanaka were all smiles as they stepped out together at London’s Nobu restaurant on Sunday night (15Jan17). Carey was accompanied by her daughter Monroe, five, who was seen being carried out of the high end eatery by her 33-year-old beau.

The night before the loved-up duo walked hand in hand as they departed a London hotel together, after the superstar performed at a Russian oligarch's granddaughter's lavish nuptials.

And it seems that Carey’s new romance has been on the cards for a while, with Tanaka expressing his interest in the singer during the latest episode of her E! reality show Mariah's World, which aired on Sunday. In the episode, the dancer says he felt saddened when he saw the mother-of-two interacting with Packer before their split.

"Seeing Mariah and James all touchy feely...it doesn't seem real, but seeing it in real life...I guess it's real. This is like a big reality check, took a lot of air out of my balloon. It just f**king sucks," he said.

After seeing Carey get fitted in a white wedding dress, Tanaka confided to his friend G. Madison that he felt like there was "some real authentic stuff" going on.

"Seeing Mariah in that dress...it's definitely a wake-up call,'" he admitted.

At the time of filming the reality show, Mariah was careful not to give too much away to her manager Stella Bulochnikov on the state of their relationship.

"I've been friends with Tanaka before I knew anyone else on this tour," she said.