The news of the reunion comes after Martin, 42, and Johnson, 29, were spotted out two nights in a row this week.
The Coldplay frontman accompanied the actress to a wrap party for her upcoming film Covers on Wednesday, July 31.
The following night, Martin joined Johnson at the Los Angeles premiere of her new film, The Peanut Butter Falcon, which hits theaters on August 9.
At the premiere, Johnson told Us and other reporters the advice she has gotten from her famous mother and grandmother, Melanie Griffith and Tippi Hedren. “Mostly just, like, don’t be an idiot,” she said.
Us Weekly exclusively confirmed in December 2017 that the duo were dating after they visited Israel together.
“Chris is very young at heart, so it makes sense for him to be with someone younger,” an insider later told Us. “That’s just one of the ways Dakota is very much his type.”
In September 2018, the 50 Shades of Grey star told Tatler that she is “very happy” with Martin, and in December, a source told Us that engagement was on the horizon for the couple. “Chris is head over heels,” the source added.
In mid-June, however, reports circulated that they split, and weeks later, a rep for Martin had to debunk rumors that the musician kissed Dua Lipa at the 2019 Glastonbury Festival.
Martin was married to Paltrow, 46, from 2003 to 2016 and shares daughter Apple, 15, and son Moses, 13, with the Avengers actress, who married TV producer Brad Falchuk last year. Johnson previously dated musician Matthew Hitt and actor Jordan Masterson.
With reporting by Brody Brown and Kayley Stumpe