The "New Love" hitmaker was snapped on a dinner date with the former "Mr. Robot" star in New York last September (20), and now it's been claimed the pair have become romantically involved.
"He is definitely dating Grace. Things have become romantic," a source told Britain's The Sun newspaper.
"Lockdown restrictions have made things more difficult, especially when he has been back in the U.K., but they are seeing how it goes and are getting along. Mark is pretty private, so he has kept the whole relationship low-key but it really seems to be heating up."
The producer is even said to have met Hollywood legend Meryl and her spouse Don Gummer and received their seal of approval.
The insider added, "They seemed to like him, which is a good sign. It would be daunting for any guy to try to charm Meryl Streep."
Since his five-year marriage to Josephine de La Baume ended in 2017, the "Nothing Breaks Like a Heart" hitmaker has romanced British actress Genevieve Gaunt and SNL talent executive Rebecca Schwartz.
Gummer, meanwhile, finalised her divorce from Tay Strathairn in August 2020.
Back in 2019, Mark Ronson identified himself as sapiosexual. When asked, "you are identifying as a man who likes intellect?" the musician replied, "Yeah, I didn't know that there was a word for it."
He later regretted his remarks, insisting he wasn't fully informed about the term. "I do not consider myself part of any marginalised community and I apologise if anybody misunderstood or took offence to it," he explained.