"I know he didn't have [a speech] fully prepared, but he is really good off the cuff, and he actually tends to do better when he doesn't plan things," Susan said backstage after the ceremony.
The actor gave one of the more amusing addresses of the evening in accepting the best comedy actor award for his Sherlock Holmes role. "I would like to thank Susan Downey for telling me that Matt Damon was going to win, so don't bother to prepare a speech," the actor began.
He went on to list several people he wouldn't be able to thank, due to his lack of preparation. "I really don't want to thank my wife," he said, "because I could be bussing tables at the Daily Grill right now, if not for her."
He added: "What am I going to do, thank Joel Silver? The guy's only restarted my career 12 times since I started 25 years ago."
Speaking to PEOPLE backstage, the actor said it was nice to be able to work with his wife on the film.
"It's much better to spend four months together than four months apart, and she's a great producer," he said.
"I think great relationships are about conflict resolution, and so we had a lot of problems to solve on the movie, and it was also about our lives together as a couple, so it worked out all right."
Of his award, Susan said: "It's great for him, it's great for the movie, and we worked, as he said, really hard, so it's so nice to have him have this recognition."