The 41-year-old star won the coveted trophy for his role of revenge-seeking fur trapper in "The Revenant".
"He's usually just cool as a cucumber, he was really chill," Robbie told People magazine.
The actress said seeing the actor on the stage was a memorable moment.
"I screamed. I literally screamed," Robbie said, adding "Everyone was beside themselves, no one would sit down, just kept clapping as he was doing his speech. It was an amazing moment.