The 46-year-old actor proudly locked lips with his Fargo co-star, 33, who he began dating shortly after his split from his estranged wife Eve Mavrakis, when he left for the stage to deliver his acceptance speech.
The film veteran headed straight over to his new girlfriend after being awarded the accolade for Outstanding Lead Actor in a Limited Series or a Movie for his role as twins Emmitt and Ray Stussy in American comedy series Fargo.
Ewan thanked Mary as well as a list of people from his team in his meaningful thank you to the crowd.
He said: “Thank you to Warren, to FX, MGM brah, that’s what we used to call you on set, MGM brah and Noah, for putting together this amazing team to make this, to give us these great scripts and amazing storylines and great characters, and really for the great directors that you gave us to work with.”
He then praised the crew of Calgary for providing them with warmth in the “amazingly cold place” where they shot some scenes.
The actor continued: “Like, it’s minus 40 degrees and they’re there, and they kept us warm, and they kept it, the whole machine moving. And they’re amazing, really, the people in Calgary.
“So, I want to thank you for all that, especially Gail Kennedy, who did all my prosthetic makeup to make me Ray, and she did an amazing job, and Chris Glimsdale who did my hair or lack of hair for both those characters. So, thank you especially to them.
”Thank you to all of our actors… and Mary.”
Ewan’s red carpet attire consisted of a white shirt accompanied with a smart black suit and a matching bow tie for the star-studded event held in Santa Monica’s Barker Hangar.
His girlfriend wore a a vibrant floor-length gown which featured yellow, peach and grey frills and styled her cropped hair to the side.
The film star’s award was among a host of other winners including Guillermo del Toro’s The Shape Of Water, which won an impressive four gongs.
Ewan’s stint in Fargo also won him a Golden Globe for Best Actor just last week.
In his speech, he once again briefly thanked Mary for his win and also praised his former wife for sticking by him through his career of “22 years”.
He said: “I want to take a moment to say thank you to Eve, who always stood by me for 22 years and my four children, Clara, Esther, Anouk and Jamyan, I love you and you know I’ve always loved being an actor and hanging out with actors and I got amazing actors to work with on this.”
“There wouldn’t have been any Emmett without David Thewlis and Michael Stuhlbard and Carrie Coon. And there wouldn’t have been any Ray without Mary Elizabeth Winstead.”
Ewan and Eve, who married in 1995, reportedly split in May last year.
The actor moved his belongings out of his family home to start a new life with the brunette actress in November, according to The Sun.
A source told the publication: “Eve was his love and supported his career. It is very sad.
“They think he might be having a mid-life crisis and that is why he is pursuing his relationship with Mary at the expense of his family.”