The pair, who both rocked black leather motorcycle jackets and jeans during the outing, were first spotted together last month, sparking rumors that McGregor had split from wife Eve Mavrakis.
As previously reported, the Trainspotting star, 46, was photographed by the The Sun kissing his Fargo costar, 32, at The Good Life Eatery in London St. John’s Wood on Sunday, October 22.
McGregor and Winstead “seemed relaxed in each other’s company,” a fellow diner at the told the publication about the new couple’s trip to the London café.
“They were deep in conversation and were there together for more than an hour,” the diner continued. “As they left she got onto the back of Ewan’s motorbike and they sped off together.”
McGregor has not commented on his presumed breakup with Mavrakis, 51, with whom he shares four daughters, Clara, 21, Jamyan, 16, Esther, 15, and Anouk, 6. The Star Wars actor and the production designer have been married for 22 years and met on the set of the British TV series Kavanagh QC.
Winstead announced her split from director Riley Stearns in May after seven years of marriage. The Scott Pilgrim vs. the World star joined the cast of Fargo as Nikki Swango during the series’ third season.
Winstead posted a picture with McGregor on Instagram in February in Canada, where the FX drama is filmed.
“Pretty lovely Canadian Sunday. Good night! ❄️,” she wrote at the time.