Ryan Gosling jumped to his feet and started clapping when his mom Donna was called to receive her diploma as she graduated with a Bachelor of Education degree from Brock University in Canada.
Ryan attended the graduation ceremony with his girlfriend Eva Mendes.
The actor maintained a low profile, despite his celebrity status.
University spokesman Kevin Cavanagh said, "He requested privacy for himself and his family. He told me this was his mom's day and the graduates' day. He didn't want to be a diversion."
He added that Ryan told him his mother will make a really great teacher and spoke of the important role she played in his own development.
Ryan refused to do any interviews with the assembled press saying "This is my mom's day."
The actor, who wore a burgundy sweater and black jeans, was spotted playing with a little boy at the graduation.
Mr Cavanagh said: "He is very fond of and proud of his mother. He was beaming."
According to reports, after the ceremony Ryan took his 38-year-old girlfriend to Niagara Falls where they rode the ferris wheel before returning to spend time with Donna.