The video, first published in The Daily Mail, reportedly shows the pair dancing together in a street in Tokyo and kissing openly near a car.
Styles, 29, is currently on his Love on Tour and performed in Japan’s capital city earlier this week. He was last in a relationship with Olivia Wilde, but the pair called it quits after nearly two years of dating.
Meanwhile, Ratajkowski has spoken candidly about her dating life following her divorce from Sebastian Bear-McClard, with whom she shares two-year-old son Sylvester Apollo Bear.
She was recently dating comedian Eric Andre and posted a photograph of them together while semi-nude on Valentine’s Day. However, she hinted at the end of a “situationship” just three days later.
According to reports, the “Watermelon Sugar” singer and the 31-year-old model shared several kisses and held hands while standing on the street in Tokyo as people walked by.
In the video, Styles appeared to be wearing a black suit with a white shirt, while Ratajkowski wore a short red puffer coat and a black skirt.
The video and screenshots shared on Twitter have prompted mixed responses from fans, some of whom are “devastated” by the potential romance.
“I did not see this coming,” one person wrote, while another simply tweeted: “Quietly sobbing.”
A third joked: “Please delete this video of my boyfriend.”
Recently, Ratajkowski opened up about how media scrutiny around her love life has affected her.
Speaking on an episode of her High Low podcast, the model said it has been “hard” to “casually date and not get cuffed up”.
“Any time I go on another date, everybody knows. So the other guys I’m dating see it, and it has been kind of difficult because, of course, they’re like, ‘Didn’t talk to her last night’, and then there’s pictures of me out to dinner with someone else. It sucks,” she said.
Ratajkowski added that it was “tricky to navigate” being photographed while on dates and leaves her “embarrassed” and “apologising” to her potential dates all the time.
Since filing for divorce from Bear last year, to whom she was married for four years, Ratajkowski has been romantically linked to comedian Pete Davidson, DJ Orazio Rispo, artist Jack Greer, Andre, and most recently, Styles.
The Independent has contacted representatives for Styles and Ratajkowski for comment.