McGregor won his first ever Globe when he took home best actor in a limited series for his role in Fargo.
Accepting his award on stage, the 46-year-old paid tribute to estranged wife Eve Mavrakis and his children.
: "I want to take a moment to just say thank you to Eve, who always stood by me for 22 years, and my four children Clara, Esther, Jamyan and Anouk."
The Star Wars actor then left viewers gobsmacked as he went on to mention 33 year old Mary Elizabeth Winstead, his Fargo co-star who he left his wife for last year..
"And I've always loved being an actor and I love hanging out with actors and I got amazing actors to work with on this.Fans took to Twitter in shock and amusement at the awkward and uncomfortable speech.
"There wouldn't have been Emmit Stussy without David Thewlis and Michael Stuhlbarg and Carrie Coon and there wouldn't have been a Ray without Mary Elizabeth Winstead."
Approached by the Daily Mail at the former marital home in Brentwood, Los Angeles, she said: "No, I did not like his speech."
Asked why, she replied: "For the same reasons you are here asking me about it. I am not going to say any more."